Jump to:

Disease/Disorder

Definition

Breast cancer is an abnormal growth or proliferation of cells within the breast tissue. It usually involves the ducts (tubes that carry milk to the nipple, ductal cancers) and lobules (glands that make milk, lobular cancers). It occurs in both men and women but is rare in men.1

Etiology

Cancer arises from a complex series of steps involving mutated genes that enhance the ability of the cells to grow. This in turn leads to the development of a tumor. The majority of cancers arise as the result of acquired gene mutations, while a small percentage occur from inherited mutations. The cancer can then spread via lymphatic vessels and lymph nodes from the breast tissue to other parts of the body.

Epidemiology including risk factors and primary prevention

The American Cancer Society (ACS) projects 281,550 new cases of breast cancer in women for 2021 with 43,600 women dying from their disease.1 While the incidence rate has increased by 0.5% per year, the death rate has decreased by 1% per year.30 Although breast cancer has traditionally been less common in non-industrialized nations, its incidence in these areas is increasing. Industrialization in developing countries is associated with rapid increases in breast cancer risk.3

Risk factors: age, family history of breast cancer, mutations in breast cancer susceptibility genes BRCA1 and BRCA2, increased exposure to endogenous estrogens (early menarche, late menopause, delayed childbearing, lower parity), a diet high in animal fat, alcohol use, obesity, physical inactivity, high breast density, and exposure to ionizing radiation.1,3

Screening with mammography with or without clinical breast exam may decrease breast cancer mortality.4 Breast MRI improves detection in those at risk with negative mammography.5

Patho-anatomy/physiology

The main stages in progression of breast cancer from normal cells are usually:6

  1. Hyperplasia: increased cell growth;
  2. Atypical hyperplasia: alteration of cell adhesion and polarity;
  3. Carcinoma in situ: appearance of increased histologic and biologic diversity in cells;
  4. Carcinoma: invasion into surrounding stroma.

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

Cancer staging by the American Joint Committee on Cancer TNM system is based on these five factors: location, size (extent of the tumor), number, lymph node involvement (the spread to nearby sites), and metastasis (spread to distant sites).7

Primary tumor (T) categories

TX: Primary tumor cannot be assessed.
T0: No evidence of primary tumor.
Tis: Carcinoma in situ (DCIS, LCIS, or Paget disease of the nipple with no associated tumor mass)
T1: (includes T1a, T1b, and T1c): Tumor is 2 cm (3/4 of an inch) or less across.
T2: Tumor is more than 2 cm but not more than 5 cm (2 inches) across.
T3: Tumor is more than 5 cm across.
T4: (includes T4a, T4b, T4c, and T4d): Tumor of any size growing into the chest wall or skin. This includes inflammatory breast cancer.

Nearby lymph nodes

NX: Nearby lymph nodes cannot be assessed (for example, if they were removed previously).
N0: Cancer has not spread to nearby lymph nodes.

  1. N0(i+): Tiny amounts of cancer are found in underarm lymph nodes by using either routine or special stains. The area of cancer spread contains less than 200 cells and is smaller than 0.2 mm.
  2. N0(mol+): Cancer cells cannot be seen in underarm lymph nodes (even using special stains), but traces of cancer cells were detected using RT-PCR.

N1: Cancer has spread to 1 to 3 axillary (underarm) lymph node(s), and/or tiny amounts of cancer are found in internal mammary lymph nodes (those near the breastbone) on sentinel lymph node biopsy.

  1. N1mi: Micrometastases (tiny areas of cancer spread) in lymph nodes under the arm. The areas of cancer spread in the lymph nodes are at least 0.2 mm across but not larger than 2mm.
  2. N1a: Cancer has spread to 1 to 3 lymph nodes under the arm with at least one area of cancer spread greater than 2 mm across.
  3. N1b: Cancer has spread to ipsilateral internal mammary lymph nodes, but this spread could only be found on sentinel lymph node biopsy (it did not cause the lymph nodes to become enlarged).
  4. N1c: Both N1a and N1b apply.

N2: Cancer has spread to 4 to 9 lymph nodes under the arm, or cancer has enlarged the internal mammary lymph nodes (either N2a or N2b, but not both).

  1. N2a: Cancer has spread to 4 to 9 lymph nodes under the arm, with at least one area of cancer spread larger than 2 mm.
  2. N2b: Cancer has spread to one or more internal mammary lymph nodes, causing them to become enlarged.

N3: Any of the following:

N3a: either

  1. Cancer has spread to 10 or more axillary lymph nodes, with at least one area of cancer spread greater than 2 mm, OR
  2. Cancer has spread to the lymph nodes under the clavicle (collar bone), with at least one area of cancer spread greater than 2 mm.

N3b: either:

  1. Cancer is found in at least one axillary lymph node (with at least one area of cancer spread greater than 2 mm) and has enlarged the internal mammary lymph nodes, OR
  2. Cancer has spread to 4 or more axillary lymph nodes (with at least one area of cancer spread greater than 2 mm), and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.

N3c: Cancer has spread to the lymph nodes above the clavicle with at least one area of cancer spread greater than 2mm.

Metastasis

M0: No distant spread is found on x-rays (or other imaging procedures) or by physical exam.

  1. cM0(i+): Small numbers of cancer cells are found in blood or bone marrow (found only by special tests), or tiny areas of cancer spread (no larger than 0.2 mm) are found in lymph nodes away from the breast.

M1: Cancer has spread to distant organs.6

Breast cancer stage grouping (0-IV) is then determined from this information with stage 0 being ductal carcinoma in situ, and stage IV being spread to distant organs or lymph nodes far from the breast. The most common sites of metastasis are the bone, brain, liver, and lung.7

Specific secondary or associated conditions and complications

Currently, there are more than 3.8 million breast cancer survivors in the United States.7Many disorders of the upper limb are associated with ipsilateral breast cancer treatment. Cancer survivors are more likely to take sick leave and less likely to be employed than those without a cancer history. Some of the conditions amenable to rehabilitation listed below are thought to be barriers to return to work.8 Although the specific incidence of these conditions is not known, rotator cuff disorders are the most common cause of shoulder pain in the general population. So, it is not surprising that this problem complicates rehabilitation in breast cancer survivors.9 Of note, multiple conditions listed below can coexist in the same patient.

Conditions requiring rehabilitation in the survivorship period include10

Musculoskeletal disorders

  1. Postsurgical pain
  2. Rotator cuff disease
  3. Adhesive capsulitis (frozen shoulder)
  4. Arthralgias (generalized or focal, associated with aromatase inhibitors)32

Neuromuscular disorders

  1. Cervical radiculopathy
  2. Brachial plexopathy
  3. Polyneuropathy
  4. Mononeuropathy
  5. Postmastectomy pain syndrome

Lymphovascular/cardiovascular disorders

  1. Lymphedema (upper extremity, truncal)
  2. Axillary web syndrome (cording)
  3. Thromboembolic disease
  4. Cardiomyopathy

Integumentary disorders

  1. Cellulitis
  2. Radiation dermatitis
  3. Radiation fibrosis
  4. Seroma11

Metabolic disorders

  1. Fatigue12
  2. Osteopenia/Osteoporosis

Neuropsychiatric disorders

  1. Cognitive dysfunction = “chemobrain”13
  2. Depression
  3. Anxiety

Essentials of Assessment

History

Age, menopausal status, family history of breast cancer, BRCA status (if known), associated pain, weakness, numbness, tingling, bladder and bowel dysfunction, cognitive changes, history of prior cancers, cancer of the contralateral breast, treatment history, assistance required at home.

Physical examination

  1. Manual examination of symptomatic and contralateral breast.
  2. Evaluation of lymph nodes.
  3. Baseline arm circumference measurements.
  4. Neuromuscular examination (pre-existing neuropathy, strength impairment, evidence of spinal metastasis).
  5. Inspection, palpation, and range of motion of joints (pre-existing arthralgias and shoulder function).

Functional assessment

Assess ability to do overhead activities, complete activities of daily living, and gait analysis. Cognitive evaluation should be done if brain metastases are present at time of presentation, or if by history there are any concerns raised. Current exercise practices of the individual patient should be reviewed.

Laboratory studies

Special laboratory testing done on the breast tissue removed usually consists of:

  1. Estrogen receptor (ER) and progesterone receptor (PR) status testing.
  2. Human epidermal growth factor receptor (HER)2/neu receptor status testing.
  3. Gene profile testing may be done by microarray assay or reverse transcription-polymerase chain reaction (e.g., MammaPrint, Oncotype DX)1

Imaging

  1. Screening mammography is recommended by ACS guidelines to be offered to women at average risk at 40 years old (risk/benefit discussion) and required annually from ages 45-54. Women ages 55 and older can get screening every other year.7
  2. According to the United States Preventive Services Task Force, screening is recommended every other year from ages 50-74. (USPTF)14
  3. Ultrasound may be used as an adjunct to mammogram. This is typically recommended in node-negative cancer, for women with dense breast tissue to visualize breast changes that are difficult to see on mammogram, and to guide biopsies. Addition of ultrasound to mammogram increases both detection of cancer and false positive rate.15
  4. MRI (Magnetic Resonance Imaging) is recommended for patients with higher risk of developing breast cancer and to determine the extent of the cancer. Although more expensive than ultrasound, MRI may detect cancers missed by mammogram or ultrasound, but also increase false positive rate. The sensitivity of mammogram, ultrasound, and MRI together is very high.15
  5. PET (Positron Emission Tomography) scans are used to assess if cancer has spread to lymph nodes or other parts of body, and also response to treatment in metastatic disease.
  6. Scintimammography, positron emission mammography (PEM), electrical impedance imaging (EIT), and elastography are all types of breast imaging being studied for use in women. 7

Supplemental assessment tools

  1. Breast biopsy (fine-needle, core needle, stereotactic, and excisional).
  2. DEXA (dual-energy X-ray absorptiometry, now called DXA) scans in post-menopausal women to evaluate bone status, which may be affected by breast cancer treatment.
  3. Cardiac testing should be performed in patients who may be started on anthracycline or trastuzumab.
  4. Serum tumor markers (e.g., CEA, CA27.29, HER-2/neu oncogene product) to help with treatment decisions and response to treatment.31

Early predictions of outcomes

Adverse prognostic factors are axillary node involvement, ER/PR negative and HER-2 neu negative (triple negative), lymphovascular invasion, and patients who are 35 years or less at diagnosis. Although data is limited, concurrent pregnancy is no longer thought to significantly change survival, even in patients with estrogen-receptor positive disease.16

Surgical treatment

Types of surgery for treatment of breast cancer include breast-conserving surgery and mastectomy. Lumpectomy, partial mastectomy, quadrantectomy, and segmental mastectomy are all types of breast-conserving surgery.7 A sentinel lymph node biopsy is the minimum done to determine if there is node involvement, which affects prognosis as above. An axillary node dissection is a more extensive surgery for patients with known node involvement.

Breast reconstruction can be performed immediately at the time of mastectomy or delayed. Delayed reconstruction is typically recommended for patients that need radiation. Timing also depends on individual patient preference. Types of surgery for breast reconstruction after treatment include tissue flaps from native muscle tissue and silicone or saline implants +/- nipple-areolar preservation.  Implant reconstruction involves initial placement of tissue expanders, gradual capsule expansion, followed by implant placement. Implants may be placed either subpectoral or prepectoral. The most common types of tissue flaps are transverse rectus abdominis muscle flaps, deep inferior epigastric perforator flaps, and latissimus dorsi flaps.7 Since these move muscle tissue that supports the core (either the abdomen or the upper back), muscle function may be affected. Smoking and elevated BMI are thought to be unfavorable factors in predicting satisfaction with reconstruction. Potential complications include capsular fibrosis and implant loss.17

For those that cannot have or do not choose reconstruction, external breast prostheses are an option. They vary in size, shape, and weight are offered commercially at supply stores. Nipple prostheses are also available. Some breast-conserving and even mastectomy may spare the nipple. Nipple loss can be a difficult adjustment for patients, and a tattoo of a nipple may be an option.

Environmental

Patients should be counseled on weight reduction through regular exercise, smoking cessation, and abstention from alcohol.

Social role and social support system

Women with breast cancer should be encouraged to continue as much of their previous personal, professional and social life as possible. They should take advantage of support from friends, family, and community sources, such as www.cancer.org, to ease the psychosocial stress associated with breast cancer and improve treatment effectiveness. Patients should be screened for premorbid psychological disorders and coping skills as these factors can play a more important role in quality of life than cancer-related variables.18 Treatment should be offered for mood and adjustment disorders. Resources should be made available as soon as possible to all patients, especially those at high risk.

Professional Issues

Applicable issues include informed consent, education of family and friends, language barriers, and the patients’ comfort in discussing their diagnosis, prognosis, and treatment. Access to the most up-to-date care is an issue, especially in socioeconomically disadvantaged populations.

Rehabilitation Management and Treatments

Available or current treatment guidelines

Oncologic management strategies available for risk reduction in high-risk women include intensive surveillance and genetic testing, chemoprevention with Selective Estrogen Receptor Modulators (SERMs) vs aromatase inhibitors, and prophylactic surgery. Surveillance, consisting of monthly breast self-examination, annual screening mammography, and clinical breast examinations once or twice yearly, does not clearly result in early detection in high-risk women.3,7

Treatment may be a combination of surgery (lumpectomy/mastectomy, sentinel lymph node biopsy, axillary lymph node dissection, reconstruction), chemotherapy, radiation, hormonal therapy (tamoxifen, aromatase inhibitors), and immunotherapy (immune checkpoint inhibitors).3,7,33 Chemotherapy may occur before or after surgery. Radiation typically occurs after resection, but before reconstruction, if possible and desirable as radiation may alter cosmesis.

Rehabilitation management depends on the impairments present (see appropriate modules.). Upper limb neuromuscular and lymphovascular disorders are typically the focus. Although many neuromuscular disorders as listed above are associated with breast cancer, and lymphedema is frequently associated with cancer, not all of these nerve dysfunctions can be attributed to lymphedema. For example, lymphedema is not likely the cause of all carpal tunnel syndrome in breast cancer patients.19

At different disease stages

Rehabilitation should begin early in order to maximize and maintain function and quality of life. Prehabilitation includes pre-operative measures of physical and psychosocial wellbeing and occurs between cancer diagnosis and beginning of acute treatment.34,35 Physical impairment from breast cancer and its treatments can arise at any stage of the disease. Accurate assessment of pain and functional disorders are key to ensuring safe and effective rehabilitation, regardless of where along the cancer continuum the patient is at a given time. It is as important for performance of activities of daily living to accurately diagnose and treat a rotator cuff tendinopathy in a patient in the final months of life as it is for one who recently finished primary treatment. Lymphedema is a common impairment seen in breast cancer patients after treatment and can be managed with manual decompression therapy and compression garments. Lymphedema management is covered in another article in PM&R KnowledgeNOW®, as are impairments from metastatic disease.

At diagnosis, prehabilitation exercises can be offered to prevent postoperative shoulder dysfunction.20 Scapular stabilization exercises are particularly helpful in this population and can be performed both before surgery and after drains have been removed.21 During chemotherapy or radiation, aerobic exercise can be helpful to combat fatigue and decreased endurance. During survivorship, patients may have more energy to focus on formal rehabilitation. Supportive care should be offered for painful conditions to maximize function. Rehabilitation and pain control also play a significant role in the palliative care patient. Evidence is increasing for the use of exercise to improve bone density not only in patients with local cancer, but also in patients with active disease metastatic to bone.22

Coordination of care

Effective collaboration and communication should take place between oncologists, surgeons, physiatrists, physical therapists, occupational therapists, case managers, psychologists, and social workers. Regular team and family meetings are helpful in coordinating care.

Patient & family education

This should focus on:

  1. Benefits of exercise for fatigue, strength, range of motion, bone health, and cancer risk reduction and information on appropriate exercise regimens.
  2. Dietary interventions and lifestyle modifications to optimize Body Mass Index
  3. Education on known side effects of specific chemotherapy agents, hormonal therapy, radiation therapy, immunotherapy agents, and surgical resection.
  4. Education on lymphedema risk and prevention, and the need to carry out lymphedema management at home (e.g., compression sleeves).
  5. Education on fertility options if treatment will affect fertility.

Emerging/unique interventions

Treatment outcomes can be measured as performance-based indicators (range of motion [ROM], 6-minute walk test, grip strength, ECOG performance status, Functional Independence Measure), and patient-reported indicators (e.g., pain, fatigue, depression, quality of life [QOL]).

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

There is considerable high-level evidence that exercise improves multiple spheres of function and quality of life in breast cancer patients, both during treatment with chemotherapy, surgery, and/or radiation, and after. Exercise was considered safe and demonstrated improved aerobic fitness, muscular strength, body size and composition, fatigue, anxiety, and quality of life during breast cancer treatment. After treatment, positive effects of exercise have been demonstrated to safely improve aerobic fitness, muscular strength, body size and composition, flexibility, fatigue, physical function, depression and anxiety, body image, quality of life, pain, range of motion, and other symptoms.23,24 Exercise is a safe and effective modality that should be incorporated where possible into the plan of care for breast cancer patients and survivors. Lymphedema should be treated with manual decompression therapy by a certified rehabilitation professional.23

Cutting Edge/Emerging and Unique Concepts and Practice

Cutting edge concepts and practice

  1. Increasing knowledge in the field of cancer genomics and cell biology will eventually lead to more effective patient-specific and less toxic treatments for breast cancer.
  2. Immune checkpoint inhibitors including PD-1 inhibitors are being tested and used as part of breast cancer treatment.33
  3. Five sub-types of breast cancer have been identified. Each sub-type has a distinct response to chemotherapy. The future will focus on the individualization of treatment for breast cancer based the genetic sub-type present.
  4. The use of liposomes as a vehicle to deliver chemotherapeutic agents directly into cancer cells, thereby sparing normal surrounding cells, is one potential treatment that offers fewer toxic effects.
  5. Prehabilitation studies continue to show improvements in body composition, emotional well-being, and quality of life in breast cancer patients.34,35
  6. At present, efficacy of a breast cancer vaccine is under review.25
  7. Fenretinide, a retinoid, causes apoptosis of breast cancer cells.27
  8. Vitamin D has been inversely associated with risk of breast cancer and further study may unlock beneficial neutraceutical strategies.28
  9. Circulating tumor cells and circulating tumor DNA levels may be used to predict outcomes for women with metastatic breast cancer.29

Gaps in the Evidence- Based Knowledge

Further study on accurate and appropriate screening for breast cancer needs to be completed as recommendations for screening continue to vary. Studies on the timing and dose of exercise (including weight bearing, resistance, and range of motion exercises) for treatment of neuromuscular and lymphovascular disorders should also be executed. The role of cytokines and human growth factors in the growth and treatment of breast cancer as well as the healing of musculoskeletal tissues after breast cancer treatment should be explored further. For example, increased IGF-1 may be associated with poorer outcome in breast cancer patients, but improved bone density and muscle strength in breast cancer survivors. Since IGF-1 may be the mechanism by which platelet rich plasma is effective in tendinopathy treatment, further exploration of regenerative therapies may prove interesting.

References

  1. URL: http://www.cancer.gov/cancertopics/pdq/treatment/breast/healthprofessional#Reference1.16. Accessed September 17, 2021.
  2. Siegel RL, Miller KD, and Jemal A. “Cancer statistics, 2015.” CA: a cancer journal for clinicians 2015;65.1: 5-29.
  3. DeVita VT, Lawrence TS, Rosenberg SA. Cancer, Principles and Practice of Oncology. 9th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011; 1578-1609.
  4. Howard JH, Bland KI. Current management and treatment strategies for breast cancer. Current opinion in obstetrics & gynecology. 2012;24(1):44-48
  5. Kuhl CK, et al. Breast MRI screening of women at average risk of breast cancer: An observational cohort study. ASCO Annual Meeting Proceedings. 2015: 33(28).
  6. Harris, Jr LM, Morrow M, Osborne KC. Diseases of the Breast. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010
  7. URL: https://www.cancer.org/cancer/breast-cancer/about.html. Accessed September 17, 2021.
  8. Silver JK, Baima J, Newman R, Galantino ML, Shockney LD. Cancer rehabilitation may improve function in survivors and decrease the economic burden of cancer to individuals and society. Work. 2013; Jan 1;46(4):455-72.
  9. Ebaugh D, Spinelli B, Schmitz KH. Shoulder impairments and their association with symptomatic rotator cuff disease in breast cancer Med Hypotheses 2011;77:481-487.
  10. Stubblefield MD and Keole N. Upper body pain and functional disorders in patients with breast cancer. PM&R, 2014:6(2); 170-183.
  11. Mukesh MB, Barnett G et al. Association of breast tumor bed seroma with post-operative complications and late normal tissue toxicity: results from the Cambridge Breast IMRT trial. Eur J Surg Oncol 2012:38(10);918–924
  12. van Vulpen, JK, Peeters PHM, Velthuis MJ, van der Wall E, and May AM. Effects of physical exercise during adjuvant breast cancer treatment on physical and psychosocial dimensions of cancer-related fatigue: a meta-analysis. Maturitas
  13. Jung MS, Zhang M, Askren MK, Berman MG, Peltier S, Hayes DF, Therrien B, Reuter-Lorenz PA, and Cimprich B. Cognitive dysfunction and symptom burden in women treated for breast cancer: a prospective behavioral and fMRI analysis. Brain imaging and behavior 2016: 1-12.
  14. http://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/breast-cancer-screening. Accessed April 9, 2016.
  15. Berg WA, Zhang Z, Lehrer D, Jong RA, Pisano ED, Barr RG, Böhm-Vélez M, Mahoney MC, Evans WP, Larsen LH, Morton MJ. Detection of breast cancer with addition of annual screening ultrasound or a single screening MRI to mammography in women with elevated breast cancer risk. JAMA 2012; Apr 4;307(13):1394-404.
  16. Theriault RL, Litton JK. Pregnancy during or after breast cancer diagnosis: what do we know and what do we need to know? Journal of Clinical Oncology. 2013 Jul 10;31(20):2521-2.
  17. Kern P, Zarth F, Kimmig R, Rezai M. Impact of age, obesity and smoking on patient satisfaction with breast implant surgery–A unicentric analysis of 318 implant reconstructions after mastectomy. Geburtshilfe und Frauenheilkunde. 2015 Jun;75(06):597-604.
  18. Brunault P, Champagne AL, Huguet G, Suzanne I, Senon JL, Gilles B, Rusch E et al. Major depressive disorder, personality disorders, and coping strategies are independent risk factors for lower quality of life in non‐metastatic breast cancer patients. Psycho‐Oncology
  19. Stubblefield, MD, Kim A, Riedel ER, and Ibanez K. Carpal tunnel syndrome in breast cancer survivors with upper extremity lymphedema. Muscle & nerve 2015:51(6); 864-869.
  20. Baima J, Reynolds SG, Edmiston K, Larkin A, Ward BM, and O’Connor A. Teaching of independent exercises for prehabilitation in breast cancer. Journal of Cancer Education 2015: 1-5.
  21. Flores AM, Dwyer K. Shoulder impairment before breast cancer surgery. J. Womens Health Phys. Therap. 2014; 38(3):118–124
  22. Rief H, Omlor G, Akbar M, Bruckner T, Rieken S, Förster R, Schlampp I, Welzel T, Bostel T, Roth HJ, Debus J. Biochemical markers of bone turnover in patients with spinal metastases after resistance training under radiotherapy–a randomized trial. BMC cancer. 2016: Mar 17;16(1):1.
  23. De Groef A, Van Kampen M, Dieltjens E, Christiaens MR, Neven P, Geraerts I, Devoogdt N. Effectiveness of postoperative physical therapy for upper-limb impairments after breast cancer treatment: a systematic review. Arch Phys Med Rehabil 2015: 96;1140–1153
  24. Silver JK, Baima J, Mayer RS. Impairment‐driven cancer rehabilitation: An essential component of quality care and survivorship. CA: a cancer journal for clinicians. 2013: Sep 1;63(5):295-317.
  25. Heery CR, Ibrahim NK, Arlen PM, Mohebtash M, Murray JL, Koenig K, Madan RA, McMahon S, Marté JL, Steinberg SM, Donahue RN. Docetaxel alone or in combination with a therapeutic cancer vaccine (PANVAC) in patients with metastatic breast cancer: A randomized clinical trial. JAMA oncology. 2015: Nov 1;1(8):1087-95.
  26. Lynch ME, Fischbach C. Biomechanical forces in the skeleton and their relevance to bone metastasis: Biology and engineering considerations. Advanced drug delivery reviews. 2014: Dec 15;79:119-34.
  27. Safdari Y, Khalili M, Ebrahimzadeh MA, Yazdani Y, Farajnia S. Natural inhibitors of PI3K/AKT signaling in breast cancer: emphasis on newly-discovered molecular mechanisms of action. Pharmacological Research. 2015: Mar 31;93:1-0.
  28. Reimers LL, Crew KD, Bradshaw PT, Santella RM, Steck SE, Sirosh I, Terry MB, Hershman DL, Shane E, Cremers S, Dworakowski E. Vitamin D-related gene polymorphisms, plasma 25-hydroxyvitamin D, and breast cancer risk. Cancer causes & control. 2015: Feb 1;26(2):187-203.
  29. Cristofanilli M, Pierga JY, Reuben J, Rademaker A, Davis AA, Peeters DJ et al. The clinical use of circulating tumor cells (CTCs) enumeration for staging of metastatic breast cancer (MBC): International expert consensus paper. Crit Rev Oncol Hematol. 2019 Feb;134:39-45. 
  30. URL: https://www.cancer.org/cancer/breast-cancer/about/how-common-is-breast-cancer.html Accessed on September 17, 2021.
  31. Hunt KK, Geoffrey RL, Strom EA, Ueno NT. Breast Cancer. 2nd ed. New York, NY: Springer; 2008; 1-561.
  32. Gupta NA, Henry L, Loprinzi CL. Management of Aromatase Inhibitor-Induced Muscoloskeletal Symptoms. JCO Oncology Practice. 2020 16;11:733-739.
  33. Gaynor N, Crown J, Collins DM. Immune checkpoint inhibitors: Key trials and an emerging role in breast cancer. Seminars in Cancer Biology. 2020.
  34. Santa Mina D, Brahmbhatt P, Lopez C, Baima J, Gillis C, Trachtenberg L, et al. The Case for Prehabilitation Prior to Breast Cancer Treatment. PM&R [Internet]. 2017;9(9):S305–16.
  35. Silver J, J B. Cancer Prehabilitation: An opportunity to decrease treatment-related morbidity, increase cancer treatment options, and improve physical and psychological health outcomes. Am J Phys Med Rehab. 2013;92:715–27.

Original Version of the Topic:

Nandita S. Keole, MD, Michael D. Stubblefield, MD, Jonas Sokolof, DO. Breast Cancer. 8/17/2012.

Previous Revision(s) of the Topic:

Jennifer Baima, MD. Breast Cancer. 9/14/2016.

Author Disclose

Christian M Custodio, MD
Nothing to Disclose

Alexandra I Gundersen, MD
Nothing to Disclose