The overall survival of patients who are initially diagnosed with metastatic breast cancer has improved by 6 months over the past 2 decades, according to a population-based study conducted in the United States.
And the improvement is associated with breast surgery after the initial diagnosis, which is a debated practice in these patients, according to the authors, led by Mary Schroeder, PhD, a health services researcher at the University of Iowa in Iowa City.
The investigators reviewed data on 21,372 metastatic patients from the Surveillance, Epidemiology, and End Results (SEER) program for two periods — 1988 to 1991 and 2007 to 2011. They found that median survival increased from 20 months in the earlier period to 26 months in the later period.
None of the patients received radiation therapy as part of their first course of treatment, and only 39% underwent surgery.
Nevertheless, surgery was found to be associated with better survival on multivariate analysis that controlled for patient characteristics, clinical characteristics, and time period (hazard ratio, 0.60; 95% confidence interval [CI], 0.57 - 0.63).
The study, which was published online today in JAMA Surgery, provides a "contemporary" look at these patients, the investigators say.
"This updates earlier reports, which described outcomes for women diagnosed as having stage IV breast cancer more than a decade ago," they explain.
So does the study suggest that patients diagnosed with metastatic breast cancer should undergo surgery?
Not necessarily, according to the investigators.
Surgery might provide "critical disease control" for some patients and "could be" a component of prolonged survival, they conclude.
But they acknowledge that surgery might be a "surrogate" for other factors that extend life but are not reviewable in the SEER data, such as systemic therapies, social support, and access to care.
Randomized clinical trials and prospective patient registries are needed to truly define the observed survival benefit seen in this study, Dr Schroeder and her colleagues note.
In fact, a randomized trial being conducted in Canada and the United States (ECOG E2108) has recently completed accrual, and a Japanese trial is nearing completion, Dr Schroeder told Medscape Medical News.
In the meantime, what should clinicians and patients do?
"I offer breast surgery selectively to patients with stage IV disease," said Lisa A. Newman, MD, MPH, director of the breast oncology program at the Henry Ford Health System in Detroit.
The goals of surgery include the reduction of the "total body burden of disease," Dr Newman, who also wrote an accompanying editorial, told Medscape Medical News.
Patients who are "more likely" to benefit in this way are "medically fit with limited distant organ involvement and with disease that is amenable to targeted endocrine and/or anti-HER2/neu therapy," she said.
But other patients might also benefit. "Evidence of metastatic focus downstaging in response to primary systemic therapy would be another feature indicating possible benefit," Dr Newman added.
And patients with "bulky, ulcerated, or fungating breast tumors represent a distinctly different scenario, where surgery might be considered purely for palliation," she added.
Metastatic patients "often" want surgery, Dr Schroeder explained. However, "most commonly," surgery is not recommended by their multidisciplinary teams.
Two recent phase 3 trials comparing surgery with no surgery in metastatic breast cancer have shown no survival benefit with surgery, Dr Newman reports in her editorial.
However, both of these studies were international, and might not be relevant in a "more affluent country such as the United States, where patients have improved access to advanced diagnostic and treatment options," she said. For example, the trial conducted in India did not include anti-HER2/neu therapy, as reported by Medscape Medical News in 2013.
If surgery does indeed improve survival, it is probably a modest benefit, Dr Schroeder and her colleagues contend.
"A large benefit for many women with stage IV breast cancer with surgery to the intact primary tumor is unlikely, especially as an ever-increasing array of more potent and targeted drugs may be able to provide better control or even eradication of systemic disease," they write.
However, their results suggest that the benefit could be long term, which is the hoped-for outcome for all metastatic cancers.
Of the 7504 patients diagnosed with metastatic disease before 2002, survival of at least 10 years was seen in 353 patients who underwent surgery and in 107 who did not (9.6% vs 2.9%; odds ratio [OR], 3.61; 95% CI, 2.89 - 4.50).
On multivariate analysis, survival of at least 10 years was associated with receipt of surgery (OR, 2.80; 95% CI, 2.08 - 3.77). Surgery was a more powerful predictor of this long-term survival than age, tumor size, year of diagnosis, marital status, race/ethnicity, or tumor receptor status, the investigators report.
This study was supported in part by the University of Iowa Holden Comprehensive Cancer Center Population Research Core, which is supported in part by a National Cancer Institute grant. The study authors and Dr Newman have disclosed no relevant financial relationships.