Pocket ObGyn – Breast Cancer
See Abbreviations
Epidemiology
- Breast cancer is the most common cancer among 2nd most common cause of cancer death in women (after lung cancer). From 1998–2007 the incid & mortality rates have decreased. Developed nations have a higher incid than developing.
- AA women have a lower incid rate, higher mortality rate, & higher stage at
Risk Factors
- Age >40 yo: 95% of breast cancers occur in women >40 yo
- FHx of breast cancer: 1st-degree relatives, premenopausal breast cancer, BRCA1 & BRCA2 mutations (tumor suppressor genes, autosomal dominant, account for 5–10% dx, but confer >80% lifetime breast cancer risk).
BRCA1/2: 50–85% risk breast cancer, 15–40% risk ovarian cancer ® risk reducing mastectomy decreases risk by 90%. BRCA testing recommended for 1st-degree relative w/ breast cancer, relative w/ breast cancer <50 yo, 3+ 1stor 2nddegree relatives w/ breast cancer, breast/ovarian cancer in 1stor 2nd-degree relative, 2+ 1stor 2nd-degree relatives w/ ovarian cancer, male breast cancer
(Obstet Gynecol 2008;111:231).
- Increased hormonal exposure: Early menarche (<12 yo), late menopause (>55 yo), older age w/ 1st Preg, fewer pregnancies (all these ® increased lifetime estrogen exposure)
- Personal h/o breast cancer: 5–1% risk of developing breast cancer in contralateral breast, majority of recurrences are w/i the 1st 5 y
- Radiation exposure: 35% lifetime risk
- Diet & exercise: Physical activity & wt control are protective
Premalignant Lesions
- Atypical hyperplasia: Ductal or lobular, proliferative lesion similar to carcinoma in situ; includes intraductal papilloma, ductal epithelial hyperplasia, sclerosing adenosis ® excision
- DCIS: Most common noninvasive breast cancer (1 of 5 new cases), usually dx by mammogram alone, can have breast conserving rx ± tramoxifen ± XRT
- LCIS: More common in premenopausal women, 1% risk/y of invasive cancer, sometimes found incidentally ® tamoxifen resection
Invasive Cancer
- Infiltrating ductal: 60–70% breast cancer; includes mucinous, tubular, & medullary carcinomas, classified by cell type, architecture of mass, & pattern of spread
- Infiltrating lobular: 10–15% breast cancer, arising in lobules, multifocal, higher incid of bilaterally
- Inflamm: 6% of breast cancer, p/w skin changes, rapid onset in a few weeks, causes diffuse induration & Dx w/ punch bx of skin & mammogram, tx w/ chemo
- Phyllodes tumor: Similar to fibroadenoma, epithelial lined spaces surrounded by monoclonal & neoplastic stromal Classified as benign, intermediate, or malignant based on atypia, mitosis, abundance of stromal cells, median age of dx 40 yo, can metastasize to distant organs w/ lung as primary site; tx w/ wide local incision.
- Paget dz: Presents as focal skin changes, assoc mass identified in 60% of Underlying DCIS in 2/3 of cases & invasive cancer in 1/3
Breast Cancer Staging/Prognosis
- Tumor size & nodal metastasis strongly correlated w/ prog
- High expression of estrogen or progesterone a/w better prog
- Overexpression of HER2 (human epidermal growth factor receptor) a/w worse prog
- ER/PR status a/w improved survival rates b/c of targeted therapy of SERMs & aromatase inhibitors (reduce circulating estrogens)
| TNM staging for breast cancer | ||
| T (tumor) | N (lymph node) | M (metastasis) |
| Tx: Tumor cannot be assessed | Nx: LN cannot be assessed | M0: No metastasis |
| T0: No evid of primary tumor | N0: No LN metastasis | M1: Distant clinical, radiologic, or histologic lesions
>0.2 mm. *All M1 dx stage 4 prior to neoadjuvant chemo |
| TIS: Carcinoma in situ | N1: Mets to movable ipsilateral level I, II axillary LNs | |
| T1 (a, b, c): Tumor <20 mm in greatest dimension | N2: Mets in ipsilateral level I, II axillary LNs clinically fixed or matted; or ipsilateral internal mammary nodes in the absence of axillary LN mets | |
| T2: Tumor >20 mm, <50 mm | N3: Mets in ipsilateral infraclavicular (level III axillary) LN w/ or w/o level I, II axillary LN involvement; or clinically detected ipsilateral internal mammary LN w/ clinically evident level I, II axillary LN mets; or mets in ipsilateral supraclavicular LN w/ or w/o axillary or internal mammary LN | |
| T3: Tumor >50 mm | ||
| T4 (a, b, c, d): Tumor of any size, direct extension to the chest wall and/or skin (ulceration/nodules) | ||
| From Edge et al. AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer; 2011. | ||
Treatment
- Depends on localization of cancer may be chemo, radiation, Surg, any combination of medical & Surg. #1 lawsuit topic for gynecologist (apart from OB): Failure to diagnose or adequately/quickly refer breast cancer (Med Law 2005;24:1).
Surg: Std of care is breast conserving Surg = lumpectomy or partial mastectomy w/ 0.5–1 cm margins often w/ preop wire localization
General Ob/Gyns refer to breast specialist or general surgeon for eval & excision