Surgery of the Breast: Principles & Art. Editor Scott L. Spear. Associate Editors: Shawna C. Willey, Geoffrey L. Robb, Dennis C. Hammond, Maurice Y. Hahabedian.
Chapter 1. Incidence, Trends, and the Epidemiology of Breast Cancer.
Reading Notes: Part I.
Breast Cancer is the most common cancer among women in North America, representing 32% of all new female cancers.
Physicians from all specialties will commonly see women with breast cancer in their practices and should understand the etiology of the disease.
Trends in Breast Cancer Incidence, Stage at Diagnosis, and Mortality
Invasive Breast Cancer
In the United States, breast caner incidence has steadily increased, with a concomitant decrease in mortality.
Stage Distribution of Breast Cancer Cases:
1995 and 2000 -- 63% of women diagnosed with breast cancer had localized disease, 29% had regional involvement, and 6% were diagnosed de novo with metastatic disease.
Improved since: 1974 and 1985 -- when the incidences were 48%, 41%, 7%.
This supports the value of screening in providing early detection. Mortality has
decreased, evidenced by the increased use of mammography.
Ductal Carcinoma in Situ (DCIS)
Ductal carcinoma in situ (DCIS) is a noninvasive form of breast cancer that may progress to invasive disease if not detected and treated.
Prior to 1970 DCIS represented 3-4% of breast cancer diagnoses and most commonly presented as a palpable mass greater than 1 cm. in diameter.
DCIS now represents 25% of new breast cancer diagnoses, and most commonly presents as clustered microcalcifications detected mammographically. DCIS is 98% curable and early detection has contributed to the observed decrease in breast cancer mortality.
Because mastectomy is associated with both physical and emotional morbidity, breast conserving surgery has been studied in DCIS patients.
Lobular Carcinoma in Situ (LCIS)
Lobular carcinoma in situ increases the risk of cancer, but it is not a premalignant lesion. Instead, it is a marker of increased risk. The conclusion is drawn from the observations that most subsequent invasive cancers are infiltrating ductal, not lobular, carcinomas and that LCIS and invasive lobular carcinoma rarely coexist in the same specimen.
The risk of breast cancer when LCIS is present is bilateral, so management should address both breasts as a single organ. Because LCIS is premalignant, there is no role for lumpectomy, radiation therapy, unilateral mastectomy, or systemic chemotherapy.
Options for LCIS:
1. One option is frequent observation because some patients may not develop cancer. This management consists of breast examination every 3-6 months with yearly mammograms and prompt workup and/or biopsy of suspicious findings. This option is designed to detect cancer, should it occur, at the earliest possible stage and is not designed to prevent cancer.
2. A second option includes bilateral prophylactic mastectomy that removes tissue at risk.
3. A third option is a 5 year course of tamoxifen. In the NSABP P-1 study, the Breast Cancer Prevention Study, tamoxifen reduced the risk of breast cancer by 56%
