Summary:

Nationwide Trends in Mastectomy for Early-Stage Breast Cancer.

Authors: Kummerow KL, Du L, Penson DF, Shyr Y, Hooks MA.

Source: JAMA Surg. January 2015;150:9-16.

There has been a lot of recent media attention to the increasing rates of bilateral mastectomy for women with unilateral breast cancer.  This trend is addressed in numerous scholarly articles, including the one above. This study showed that about one third of women with early stage breast cancer, which is likely to be suitable for breast-conserving treatment (lumpectomy), choose to undergo mastectomy for treatment and that this rate changed little between 1998 and 2011.  However, the rate of contralateral mastectomy (to remove the other breast that does not have any known disease) in women undergoing mastectomy increased from about 2% in 1998 to 11% in 2011, according to this national study.  

What then are the reasons for this increase in ‘double mastectomy’ for cancer in one breast and what should patients consider when making their decision? There are many factors to consider, including the patient’s age and other medical conditions, the individual’s risk of developing a future cancer in the other breast, the risks of the added surgical procedure, cosmesis and symmetry and the need for future screening. The question regarding contralateral prophylactic mastectomy highlights the importance of patient education and shared decision-making based on risks and benefits.

In most cases, women do not need to have both of their breasts removed after a diagnosis of cancer in one breast in order to maximize their survival.  For most women, removing the normal breast does not improve survival or decrease the risk of cancer coming back. The actual risk of developing a cancer in the other breast is low, estimated to be 0.1% per year for women with estrogen receptor-positive cancer and 0.5 to 1% per year for women with estrogen receptor-negative cancer.

Patients who may have an improvement in survival from double mastectomy include those who are very young at the time of diagnosis (less than age 35) and those that have an inherited predisposition to breast cancer such as BRCA 1 or 2 mutation.  There is limited data that for these subsets of breast cancer patients bilateral mastectomy may improve survival.  

Nonetheless, many women do consider double mastectomy. One reason is concerns regarding symmetry, especially for women with large or ptotic breasts and/or when immediate breast reconstruction is planned. Aesthetics may be very important for psychosocial functioning in the long-term.  However, patients also should consider the loss of both nipple and chest wall sensation that occurs with mastectomy. Future screening for breast cancer in the remaining contralateral breast, both in terms of finances and psychological stress, is another reason women consider contralateral mastectomy. This may be especially relevant when the detection of the index cancer was difficult.  While screening for breast cancer is not perfect, we have seen great advances over the past decade and anticipate continued advances in screening options in the future (such as MBI, MRI, PEM).  

It has been clearly documented that patients overestimate their risk of breast cancer in the other breast. Some patients think that surgery to remove both breasts will improve their chance of cure. This is not so.  Survival is determined by the stage of the tumor (size and lymph node involvement) along with tumor biology (including estrogen and progesterone receptor and HER2 status).  For women with more advanced breast cancer the risk of disease coming back is much higher than the risk of developing a new breast cancer in the other breast.

Surgery is never without risks for complications. Luckily breast surgery is very safe. However, when comparing a single mastectomy to a double mastectomy, the risk of a complication at the mastectomy site (such as infection or bleeding) essentially doubles. These risks are higher in obese women and those with diabetes and other medical co-morbidities. Issues of sexuality and limitations of breast reconstruction including the insensate nature of most reconstructed breasts also should be considered carefully verus maintaining the natural breast and its sensation.

In the end it is the patient, guided by her breast surgeon, who will make the decision on whether or not to pursue contralateral prophylactic mastectomy when she needs or chooses mastectomy for the treatment of her unilateral breast cancer.  It is interesting that in Canada and Europe rates of double mastectomy remain low, whereas in America they are significantly higher and increasing. It is important that the patient is well-educated on her choices and that decisions are not made based on unfounded fears or misinformation.