February 01, 2016
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Novel score predicts survival benefit from radiotherapy for DCIS

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A prognostic score based on nuclear grade, patient age and tumor size predicted survival benefit from radiation therapy following surgery for ductal carcinoma in situ, according to findings from a population-based cohort study.

Radiation therapy conferred a more significant survival advantage among patients with a higher prognostic score, results showed.

Yasuaki Sagara MD

Yasuaki Sagara MD

Although the benefits of radiation therapy following breast-conserving surgery have been established for patients with invasive disease, a survival benefit of radiotherapy has not been clearly established for patients with ductal carcinoma in situ (DCIS).

“DCIS has a very low breast cancer mortality, which means that as an oncology community, we must be cognizant of overtreatment,” Mehra Golshan, MD, FACS, the Al-Tuwaijri Family distinguished chair of surgical oncology at Dana-Farber Cancer Institute and Brigham and Women’s Cancer Center, said in a press release. “Our results provide information that can guide individual treatment options, and better predict survival benefit from radiation therapy based on an individual’s case.”

Golshan and colleagues sought to determine the specific survival benefit of radiotherapy after breast-conserving surgery among variable risk subpopulations of patients with DCIS.

The investigators used the SEER database to identify 32,144 patients who were first diagnosed with DCIS between 1988 and 2007. Sixty-three percent of the patients had received radiotherapy following breast-conserving surgery.

After a median follow-up of 8 years (range, 5.75-10.58 years), there were 304 breast cancer-specific deaths (0.9%). The cumulative incidence of breast cancer mortality at 10 years in the weighted cohorts was 1.8% for those who received radiotherapy and 2.1% for those who did not receive radiotherapy (HR = 0.73; 95% CI, 0.62-0.88).

After adjusting for clinical factors, the researchers found observed benefit from radiation was associated with age (P = .004), nuclear grade (P = .007) and tumor size (P = .02).

Researchers then assigned patients a validated prognostic score from 0 to 6 based on these three risk factors, with a higher score indicating higher nuclear age, younger age and/or larger DCIS.

Overall, the magnitude of the survival difference with radiotherapy was significantly correlated with prognostic score (P < .001).

Patients with a score of 4 or 5 experienced approximately a 70% reduction in breast cancer mortality if they received radiotherapy (score 4, absolute difference, 1.9%; HR = 0.31; 95% CI, 0.16-0.58; score 5, absolute difference, 4%; HR = 0.29; 95% CI, 0.09-0.91).

Patients with lower scores did not demonstrate a significant difference in breast cancer mortality (score 0, absolute difference, –0.4%; HR = 1.2; 95% CI, 0.67-2.06; score 1, absolute difference, –0.5%; HR = 1; 95% CI, 0.7-1.45).

“Using three factors that are routinely measured, we can predict whether there will be a survival benefit or no survival benefit for patients receiving radiation therapy,” Yasuaki Sagara MD, a visiting research scholar at Brigham and Women’s Hospital and Dana-Farber Cancer Institute and chief of breast oncology at Hakuaikai Medical Cooperation in Japan, said in the release. “Our finding suggests, for the first time, that patients with more aggressive cancer who are at higher risk, may actually live longer if they are treated with radiation therapy.”

The study does have several limitations. The results may be influenced by the unavailability of unmeasured confounders such as surgical margin status, endocrine therapy, patient comorbidities and reason for treatment selection.

The researchers concluded that although radiotherapy provides negligible survival benefits for low risk patients, other studies have found that it can reduce the rate of local recurrence even among patients with lower prognostic scores. As such, they recommended thorough counseling about the risks and benefits of radiotherapy. – by Anthony SanFilippo

Disclosure: Golshan reports a consulting/advisory roles with AbbVie. Sagara reports no relevant financial disclosures. One other researcher reports research funding from Eisai, Genentech and Puma.