Prophylactic Mastectomy

Prophylactic mastectomy for the prevention of breast cancer

BACKGROUND

Recent progress in understanding the genetic basis of breast cancer has increased interest in prophylactic mastectomy (PM) as a method of preventing breast cancer.

OBJECTIVES

(i) To determine whether prophylactic mastectomy reduces death rates from any cause in women who have never had breast cancer and in women who have a history of breast cancer in one breast, and (ii) to examine the effect of prophylactic mastectomy on other endpoints, including breast cancer incidence, breast cancer mortality, disease-free survival, physical morbidity, and psychosocial outcomes.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2002), MEDLINE and Cancerlit (1966 to June 2006), EMBASE (1974 to June 2006), and the WHO International Clinical Trials Registry Platform (WHO ICTRP) search portal (until June 2006). Studies in English were included.

SELECTION CRITERIA

Participants included women at risk for breast cancer in at least one breast. Interventions included all types of mastectomy performed for the purpose of preventing breast cancer.

DATA COLLECTION AND ANALYSIS

At least two authors independently abstracted data. Data were summarized descriptively; quantitative meta-analysis was not feasible due to heterogeneity of study designs and insufficient reporting. Data were analyzed separately for bilateral prophylactic mastectomy (BPM) and contralateral prophylactic mastectomy (CPM).

MAIN RESULTS

All 39 included studies were observational studies with some methodological limitations; randomized trials were absent. The studies presented data on 7,384 women with a wide range of risk factors for breast cancer who underwent PM.BPM studies on the incidence of breast cancer and/or disease-specific mortality reported reductions after BPM particularly for those with BRCA1/2 mutations. For CPM, studies consistently reported reductions in incidence of contralateral breast cancer but were inconsistent about improvements in disease-specific survival. Only one study attempted to control for multiple differences between intervention groups and this study showed no overall survival advantage for CPM at 15 years. Another study showed significantly improved survival following CPM but after adjusting for bilateral prophylactic oophorectomy, the CPM effect on all-cause mortality was no longer significant.Sixteen studies assessed psychosocial measures; most reported high levels of satisfaction with the decision to have PM but more variable satisfaction with cosmetic results. Worry over breast cancer was significantly reduced after BPM when compared both to baseline worry levels and to the groups who opted for surveillance rather than BPM.Case series reporting on adverse events from PM with or without reconstruction reported rates of unanticipated re-operations from 4% in those without reconstruction to 49% in patients with reconstruction.

AUTHORS' CONCLUSIONS

Sixteen studies have been published since the last version of the review, without altering our conclusions. While published observational studies demonstrated that BPM was effective in reducing both the incidence of, and death from, breast cancer, more rigorous prospective studies (ideally randomized trials) are needed. BPM should be considered only among those at very high risk of disease. There is insufficient evidence that CPM improves survival and studies that control for multiple confounding variables are needed.

Prophylactic mastectomy for the prevention of breast cancer

BACKGROUND

Breast cancer is the most common cancer and the second most common cause of cancer-related death among North American and Western European women. Recent progress in understanding the genetic basis of breast cancer, along with rising incidence rates, have resulted in increased interest in prophylactic mastectomy as a method of preventing breast cancer, particularly in those with familial susceptibility.

OBJECTIVES

The primary objective was to determine whether prophylactic mastectomy reduces death from any cause in women who have never had breast cancer and in women who have a history of breast cancer in one breast. The secondary objective was to examine the effect of prophylactic mastectomy on other endpoints including breast cancer incidence, breast cancer mortality, disease-free survival, physical morbidity, and psychosocial outcomes.

SEARCH STRATEGY

Electronic searches were performed in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Cancerlit, and the Science Citation Index.

SELECTION CRITERIA

Inclusion criteria were studies in English of any design type including randomized or nonrandomized controlled trials, cohort studies, case-control studies, and case series with at least ten participants. Participants included women at risk for breast cancer in at least one breast. Interventions included all types of mastectomy performed for the purpose of preventing breast cancer, including subcutaneous mastectomy, total or simple mastectomy, modified radical mastectomy, and radical mastectomy.

DATA COLLECTION AND ANALYSIS

Information on patients, interventions, methods, and results were extracted by at least two independent reviewers. Methodological quality was assessed based on how well each study minimized potential selection bias, performance bias, detection bias, and attrition bias. Data for each study were summarized descriptively; quantitative meta-analysis was not feasible due to heterogeneity of study designs and insufficient reporting. Data were analyzed separately for bilateral prophylactic mastectomy (BPM) and contralateral prophylactic mastectomy (CPM).

MAIN RESULTS

Twenty-three studies, including more than 4,000 patients, met inclusion criteria. No randomized or nonrandomized controlled trials were found. Most studies were either case series or cohort studies. All studies had methodological limitations, with the most common source of potential bias being systematic differences between the intervention and comparison groups that could potentially be associated with a particular outcome. Thirteen studies assessed the effectiveness of BPM. No study assessed all-cause mortality after BPM. All studies reporting on incidence of breast cancer and disease-specific mortality reported reductions after BPM. Nine studies assessed psychosocial measures; most reported high levels of satisfaction with the decision to have prophylactic mastectomy (PM) but more variable satisfaction with cosmetic results. Only one study assessed satisfaction with the psychological support provided by healthcare personnel during risk counseling and showed that more women were dissatisfied than satisfied with the support they received in the healthcare setting. Worry over breast cancer was significantly reduced after BPM when compared both to baseline worry levels and to the groups who opted for surveillance rather than BPM. Three studies reported body image/feelings of femininity outcomes, and all reported that a substantial minority (about 20%) reported BPM had adverse effects on those domains. Six studies assessed contralateral prophylactic mastectomy. Studies consistently reported reductions in contralateral incidence of breast cancer but were inconsistent about improvements in disease-specific survival. Only one study attempted to control for multiple differences between intervention groups, and this study showed no overall survival advantage for CPM at 15 years. Two case series were exclusively focused on adverse events from prophylactic mastectomy with reconstruction, and both reported rates of unanticipated re-operations from 30% to 49%.

REVIEWERS' CONCLUSIONS

While published observational studies demonstrated that BPM was effective in reducing both the incidence of, and death from, breast cancer, more rigorous prospective studies (ideally randomized trials) are needed. The studies need to be of sufficient duration and make better attempts to control for selection biases to arrive at better estimates of risk reduction. The state of the science is far from exact in predicting who will get or who will die from breast cancer. By one estimate, most of the women deemed high risk by family history (but not necessarily BRCA 1 or 2 mutation carriers) who underwent these procedures would not have died from breast cancer, even without prophylactic surgery. Therefore, women need to understand that this procedure should be considered only among those at very high risk of the disease. For women who had already been diagnosed with a primary tumor, the data were particularly lacking for indications for contralateral prophylactic mastectomy. While it appeared that contralateral mastectomy may reduce the incidence of cancer in the contralateral breast, there was insufficient evidence about whether, and for whom, CPM actually improved survival. Physical morbidity is not uncommon following PM, and many women underwent unanticipated re-operations (usually due to problems with reconstruction); however, these data need to be updated to reflect changes in surgical procedures and reconstruction. Regarding psychosocial outcomes, women generally reported satisfaction with their decisions to have PM but reported satisfaction less consistently for cosmetic outcomes, with diminished satisfaction often due to surgical complications. Therefore, physical morbidity and post-operative surgical complications were areas that should be considered when deciding about PM. With regard to emotional well-being, most women recovered well postoperatively, reporting reduced cancer worry and showing reduced psychological morbidity from their baseline measures; exceptions also have been noted. Of the psychosocial outcomes measured, body image and feelings of femininity were the most adversely affected.

Detection of recurrent breast cancer after TRAM flap reconstruction

Breast cancer remains a significant cause of morbidity and mortality among women today. The transverse rectus abdominis myocutaneous (TRAM) flap has played a substantial role in the reconstruction of defects secondary to mastectomy. Although such reconstruction has not been shown to adversely affect survival or local recurrence, specific screening modalities for recurrence in this population of patients have not been delineated. Three patients were examined retrospectively at the authors' institution. They presented with local recurrences of breast cancer after mastectomy and TRAM flap reconstruction. All patients' recurrences were detected on physical examination, and all had the diagnosis of recurrent carcinoma made on biopsy of the mass. A review of the literature demonstrates that mammography, ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), scintimammography, and biopsy have all been used as adjuncts to clinical examination in detecting recurrence. Subsequent treatment of recurrent breast cancer is determined by the results of a metastatic workup and the receptor status of the tumor. The most reliable form of diagnosis of recurrent breast cancer after TRAM flap reconstruction remains fine-needle, core, or open biopsy if indicated.

Breast cancer chemoprevention

Chemoprevention of breast cancer is a rapidly growing field. Chemoprevention was initiated with the development of the antiestrogen tamoxifen. A major clinical trial in the United States found that tamoxifen reduced the incidence of breast cancer by almost 50% in women at an increased risk for the disease. Although two European trials did not confirm these findings, the Food and Drug Administration found the American studies significant enough to approve tamoxifen for the delaying of breast cancer in women at high risk for the disease. However, adverse effects associated with tamoxifen include a minimally increased rate of endometrial cancer, cataracts, and strokes. Newer classes of antiestrogens, called selective estrogen receptor modulators (SERMs), are being investigated as potential chemopreventive agents. These SERMS, such as raloxifene, will hopefully provide some of the benefits of estrogen without its inherent risks. In addition, naturally occurring compounds and their analogues are also under investigation.

Breast cancer prevention by antiestrogens

A new era has been entered with the first demonstration that an antiestrogen can prevent breast cancer. In a landmark study tamoxifen was shown to reduce the incidence of breast cancer by approximately 50%. The reduction was observed in pre- and postmenopausal women at increased risk of breast cancer. Invasive cancers were reduced, the reduction being in the estrogen receptor-positive cancers. No preventive effect was observed for estrogen receptor-negative tumors. In situ cancers were also significantly reduced. A collateral benefit was a significant reduction in fractures due to osteoporosis. Adverse effects included a very small increase in the incidence of endometrial cancer, cataracts, and stroke. The benefits appear to outweigh the risks for those at high risk. Preliminary studies of a new selective estrogen receptor modulator (SERM 2), raloxifene, developed for the prevention of osteoporosis, have shown that the breast cancer rate was reduced by more than 50% without any concomitant increase in endometrial cancer. The search for a SERM 3, and beyond, may lead to the development of drugs that have the beneficial effects of estrogen while preventing breast cancer and osteoporosis.

Chemoprevention of breast cancer

A critical question is, why do the European studies fail to confirm the US study? Clearly, the answers are complex and uncertain. Differences in power, age, risk, compliance, the use of ERT, and follow-up in the European studies may all be relevant. The efficacy of tamoxifen in BRCA 1 or 2 carriers is an important issue; recent data have shown a DNA repair defect in those with BRCA 1 gene alterations. This finding, coupled with the potential genotoxicity of tamoxifen, is of concern, but the NSABP study did show a significant reduction in breast cancer risk in those with first-degree relatives with breast cancer, including those likely to have a hereditary-predisposition gene. The issue will be clarified when the BRCA 1 or 2 status of these individuals is determined from the stored DNA samples of all participants in the NSABP study. The duration of use of an antiestrogen for prevention is uncertain; the adjuvant trial data for up to 5 years of tamoxifen use showed an effect on contralateral breast cancer prevention extending beyond 5 years, but experimental data show that stopping tamoxifen therapy results in the appearance of new tumors. The long-term use of tamoxifen for prevention carries significant risks. If raloxifene can be given long term, then continuing the prevention of tumors may be possible if raloxifene is proven safe. Should tamoxifen be used outside of a clinical trial? The FDA has approved its use to "delay" breast cancer so it can be prescribed for any patient at increased risk for breast cancer. The word prevention has been the subject of polemics. Every day that breast cancer is delayed is a day that it is prevented. Risk reduction is technically a more accurate phrase but lacks meaning to many women. Novel approaches to chemoprevention are being explored. Naturally occurring compounds or their analogues are being assessed. Based on experimental studies, the vitamin A analogue 4-hydroxyphenyl retinamide (4-HPR) was shown to delay and reduce carcinogen-induced breast cancer. A randomized clinical trial of 4-HPR is being tested in women in Italy to reduce contralateral breast cancer, but no results are available. New approaches using substances derived from plants, such as vegetables, are being pursued. Based on epidemiologic studies, investigators have proposed that an estrogen metabolite, C16 alpha-hydroxyesterone (16 alpha-OHE1), may have estrogen-stimulating and DNA-damaging properties of mammary epithelial cells. Strategies to reduce 16 alpha-OHE1 have been explored. Indole-3-carbinol, found in high concentration in cruciferous vegetables (i.e., cabbage, cauliflower, broccoli, rabe, brussels sprouts, kale, and bok choi), has been shown to reduce mammary cancer in rodent models and induces a metabolic pathway competing with 16 alpha-OHE1, which increases C-2 hydroxyesterone and thereby reduces substrate available for the 16 alpha-OHE1 pathway. Indole-3-carbinol has a good short-term safety profile. The minimum effective dose that favorably perturbs the ratio between 16 alpha-OHE1 and 2-OHE1 has been determined, and a pilot feasibility trial is in progress in women at risk for breast cancer at Strang Cancer Prevention Center. Future research will identify single or a combination of agents that may significantly reduce the risk for breast cancer without toxicity. A better understanding of the steps involved in the progression of normal breast cells toward cancer will permit the development of strategies to reduce the incidence of and mortality from breast cancer, with the ultimate goal of prevention.

The evaluation of high risk and pre-invasive breast lesions and the decision process for follow up and surgical intervention

Atypical epithelial hyperplasia, lobular carcinoma in situ (lobular neoplasia), radial scar, and ductal carcinoma in situ are considered high-risk lesions that predispose toward the future development of non-invasive or invasive breast cancer. Generally, those women with atypical epithelial hyperplasia, radial scar, or lobular carcinoma in situ can be managed conservatively by close surveillance. The minority of women may consider prophylactic mastectomy. Ductal carcinoma in situ can usually be managed by lumpectomy with or without radiation, with some patients requiring mastectomy due to extensive disease.