Having breast cancer in one breast increases a woman's chances of getting breast cancer in the second breast at some point in her lifetime. A study in the March issue of Cancer addresses a question which women facing mastectomy for breast cancer have been asking doctors for years.... should I have my other ("good") breast removed as well to decrease my risk of future breast cancer in the other breast? Here's the study abstract....
"Predictors of contralateral breast cancer in patients with unilateral breast cancer undergoing contralateral prophylactic mastectomy." Min Yi, Funda Meric-Bernstam, Lavinia P. Middleton, et al. CANCER Print Issue Date: March 1, 2009
BACKGROUND: Although contralateral prophylactic mastectomy (CPM) reduced the risk of contralateral breast cancer in unilateral breast cancer patients, it was difficult to predict which patients were most likely to benefit from the procedure. The objective of this study was to identify the clinicopathologic factors that predict contralateral breast cancer and thereby inform decisions regarding performing CPM in unilateral breast cancer patients.
METHODS: A total of 542 unilateral breast cancer patients who underwent CPM at The University of Texas M. D. Anderson Cancer Center from January 2000 to April 2007 were included in the current study. A logistic regression analysis was used to identify clinicopathologic factors that predict contralateral breast cancer.
RESULTS: Of the 542 patients included in this study, 25 (5%) had an occult malignancy in the contralateral breast. Eighty-two patients (15%) had moderate-risk to high-risk histologic findings identified at final pathologic evaluation of the contralateral breast. Multivariate analysis revealed that 3 independent factors predicted malignancy in the contralateral breast: an ipsilateral invasive lobular histology, an ipsilateral multicentric tumor, and a 5-year Gail risk 1.67%. Multivariate analysis also revealed that an age 50 years at the time of the initial cancer diagnosis and an additional ipsilateral moderate-risk to high-risk pathology were independent predictors of moderate-risk to high-risk histologic findings in the contralateral breast.
CONCLUSIONS: The findings indicated that CPM may be a rational choice for breast cancer patients who have a 5-year Gail risk 1.67%, an additional ipsilateral moderate-risk to high-risk pathology, an ipsilateral multicentric tumor, or an ipsilateral tumor of invasive lobular histology.
So what does all this mean?
This study basically concludes that prophylactic (ie preventive) mastectomy should be recommended to breast cancer patients in the following situations:
1) the breast cancer is particularly aggressive or invasive
2) the biopsy pathology report shows high risk histology (such as "invasive lobular" disease)
3) there are multiple tumors in the same breast
4) a 5-year Gail risk of at least 1.67 - The "Gail risk" assesses a woman's risk of developing breast cancer by looking at a number of health factors including her medical history, race, age and more.
5) age 50 or older at the time of the first breast cancer diagnosis
This study is helpful. I'd like to expand a little on the effect age has on risk of future disease. Many doctors (including myself) recommend prophylactic mastectomy to young women, particularly if they have a family history of breast cancer, as these women have the highest overall risk of getting another cancer in their lifetime. Previous studies have shown that breast cancer patients have close to a 1% risk of another cancer per year. This risk is cumulative, in other words, it adds up: 1 % risk after 1 year, 10% risk after 10 years, 30% after 30 years, and so on. This cumulative risk is important to remember.
While I applaud this study and think it's results are very useful, I also think it is imperative that doctors remember the primary indication for prophylactic mastectomy: the patient's wishes. Breast cancer is such a devastating disease both physically and emotionally. We can educate our patients all we want about study results but we must not forget the erosive nature of anxiety over the possibility of a second breast cancer in the future. If one of my patients wants a prophylactic mastectomy even after discussing the studies, that's good enough for me.