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Breast-conserving therapy may increase local recurrence risk in younger women
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Younger women with early-stage breast cancer who received breast-conserving therapy with radiation experienced an increased 20-year risk for local recurrence compared with women who opted for mastectomy alone, according to the results of a population-based cohort study presented at the European Society for Therapeutic Radiology and Oncology conference.
Further, local recurrence increased the risk for distant metastases, and women who received breast-conserving therapy (BCT) had higher mortality risks.
However, these findings did not persist among women older than 45 years.
“These findings are in line with long-term data reported from several randomized trials, confirming that it is safe to offer older, lymph-node negative patients breast-conserving therapy and adjuvant radiation therapy,” Tinne Laurberg, MD, of the department of experimental clinical oncology at Aarhus University Hospital in Denmark, said in a press release. “When future treatments of young lymph-node negative patients are refined, the possibility of the negative impact of BCT on survival in these younger women should be taken into account.”
Because optimal local treatment for young women with early-stage breast cancer remains controversial, Laurberg and colleagues evaluated rate of local recurrence over time after BCT or mastectomy.
Researchers also sought to investigate if local recurrence was associated with excess risk for distant metastasis, and if distant metastasis was linked to higher mortality rate after BCT, particularly in younger women.
“In six randomized controlled trials comparing mastectomy and BCT, all studies had a low proportion of young breast cancer patients included, making it hard to draw any conclusion for this sub-group," Laurberg said. “In contrast to former studies, our study of young breast cancer patients was unbiased, all patients were lymph-node negative, they received only BCT or mastectomy and we had complete 20-year data on local recurrence and OS.”
The analysis included data from 1,077 Danish women diagnosed with low-risk (lymph-node negative, tumor size < 5 cm) breast cancer between 1989 and 1998. Women underwent mastectomy (n = 712) or BCT (n = 364) without systemic therapy and 305 women were aged younger than 41 years.
After 20 years, local recurrence developed in 18% (n = 66) of patients treated with BCT compared with 6.7% (n = 55) of patients who underwent mastectomy.
Incidence of local recurrence varied by age and treatment. Older patients in the mastectomy group tended to develop local recurrence within 5 years of treatment, whereas younger mastectomy patients developed local recurrence up to 10 years following treatment.
Patients in the BCT group developed local recurrence throughout the 20-year period regardless of age.
Among younger patients, those who received BCT experienced a 13% (95% CI, 4.8-20) increased risk for local recurrence after 20 years compared with those who underwent mastectomy.
Further, local recurrence was a prognostic marker for distant metastasis (HR = 2; 95% CI, 1.3-3.1). Women who received BCT also experienced greater risks for breast cancer-related death (HR = 1.6, 95% CI, 1-2.5) and all-cause mortality (HR = 1.7, 95% CI, 1.1-2.6).
For older patients, local recurrence was not a prognostic marker for distant metastasis (HR = 0.9, 95% CI, 0.3-2.2), and neither BCT nor mastectomy increased risk for breast cancer death (HR = 0.8, 95% CI, 0.5-1.2).
This study exemplifies the importance of optimal local tumor control to reduce risk for distant metastasis, according to Philip Poortmans, MD, PhD, head of department of radiation oncology at Radboud University Medical Center in Nijmegen, the Netherlands, as well as president of ESTRO.
“We have to view this [study] from the right perspective, though, as we have witnessed a remarkable decrease in the rate of local recurrences after BCT, even for young patients,” Poortmans said in the press release. “On the other hand, these results might also be a warning signal about the possible risks associated with the recent trend towards the use of less aggressive breast cancer treatments, particularly those aimed at the area of the primary tumor.” – by Nick Andrews
Reference:
Laurberg T, et al. Abstract OC–0052. Presented at: ESTRO 35 conference; April 29-May 3, 2016; Turin, Italy.
Disclosure: The study was funded by the Danish Breast Cancer Group and by the Danish Centre for Interventional Research in Radiation Oncology.