LAS VEGAS – Overall survival was better when women with occult breast cancer had axillary lymph node dissection and radiation, instead of mastectomy, in a database review of 934 cases by the University of Maryland Medical Center, Baltimore, the largest review to date of how best to handle the problem.
Five- and 10-year overall survival was 90.8% and 84.8%, respectively, among the 342 women treated with axillary lymph node dissection (ALND) plus adjuvant radiation, versus 80.0% and 69.8% among the 592 who had ALND and mastectomies, plus or minus radiation, according to an analysis of the National Cancer Database from 2004-2013. The results were presented at the annual meeting of the American Society of Breast Surgeons.
ALND plus radiation was independently associated with overall survival on multivariate analysis (HR 0.51, 95% CI 0.32-0.81, P = .004), and was associated with fewer comorbidities, use of chemotherapy, number of positive nodes, and number of nodes examined, compared with mastectomy.
Women treated with ALND plus radiation “had significantly better overall survival than those treated with mastectomy, even after adjusting for other covariates. We believe the study supports overall use of this treatment approach in patients with occult breast cancer,” said lead investigator, Lindsay Hessler, MD, of University of Maryland, Baltimore.
Occult breast cancer – axillary lymph node metastases without clinical or radiologic evidence of a primary breast tumor – is rare and accounted for less than 0.1% of the 2.03 million breast cancer cases in the database. It’s been unclear how best to treat it; most of the previous investigations were small single-center series and case reports.
The only other significant review was smaller, with 750 women in the Surveillance, Epidemiology, and End Results database treated from 1983 to 2006, the “vast majority” before routine use of breast MRI. It showed that “definitive locoregional treatment with either mastectomy or [radiation therapy] improves [overall survival] in patients with occult breast cancer and axillary metastasis who undergo ALND,” but it didn’t suggest which option is best. The National Comprehensive Cancer Network recommends either approach ().
The new University of Maryland findings “confirm that women do not need to have a mastectomy if you can’t find the cancer in their breast. Women do better if you radiate the breast instead of removing it. A lot of academic centers are doing this now, but some people don’t know about it. This needs to be implemented in a more widespread fashion,” said Shelley Hwang, MD, a surgical oncologist at Duke University, Durham, N.C., who moderated Dr. Hessler’s presentation.
Indeed, patients were most likely to be treated with radiation and ALND at an academic center (OR 2.03, 95% CI 1.5-2.74, P less than .001), the only factor on multivariate analysis related to treatment choice.
The review excluded women with only internal mammary lymph node involvement, those with lumpectomies, and women who had less than four nodes recovered on ALND. Mastectomy and radiation patients were similar in nodal stage, race, income, insurance, estrogen receptor status, comorbidities, and year of diagnosis. On pathology, a tumor was found in about a third of the patients who had mastectomies. MRI use and recurrence rates were unavailable in the National Cancer Database.
The findings are subject to all the limits of database reviews, including the possible confounder that women treated at university hospitals might also have had more optimal systemic therapy, as an audience member noted.
The investigators said they had no financial disclosures.