Which Women With DCIS Can Forgo Radiotherapy?

Veronica Hackethal, MD

February 10, 2016

A commonly used scoring system can identify a subgroup of women with ductal carcinoma in situ (DCIS) who may have improved survival when they receive radiation after lumpectomy, according to a new study. At the same time, the findings suggest that a substantial number of patients with DCIS might not need radiation.

The findings come from a study published online on February 1 in the Journal of Clinical Oncology.

"In the United States and many parts of the world, we are overtreating DCIS," said lead author Mehra Golshan, MD, distinguished chair of surgical oncology at Brigham and Women's Hospital/Dana-Farber Cancer Institute in Boston.

"With this prognostic score we were able to stratify some women who don't derive a survival benefit from radiation therapy," Dr Golshan told Medscape Medical News. However, there is a suggestion that for some breast cancer subgroups — such as younger patients, those with higher-grade disease, and those with larger amounts of disease — survival might be better with radiation therapy.

The prognostic scoring system has been validated and used for quite some time, Dr Golshan explained. It was originally devised to predict recurrence, and uses easily identifiable factors obtained from any pathology report done anywhere in the world: patient age, tumor grade, and tumor size.

DCIS affects more than 60,000 people in the United States each year, according to Dr Golshan. Recurrence rates are very low and survival is over 98%. Although different treatments (lumpectomy, lumpectomy with radiation, and mastectomy) have different local recurrence rates, doctors have commonly thought that they result in equivalent survival.

Not so, according to Dr Golshan's team. They are the first to say that survival might not be exactly the same for a subset of patients.

"This is the first time it's ever been shown that there are women with DCIS whose survival could be improved by getting radiation after lumpectomy, but that many women — most women — probably won't live longer by getting radiation therapy," Dr Golshan said.

Study Details

In the retrospective longitudinal study, researchers used the National Cancer Institute SEER database, which contains data on cancer incidence and survival from many population-based cancer registries.

They identified 32,144 patients treated for DCIS from 1988 to 2007, 20,329 (63%) of whom received breast surgery plus radiation and 11,815 (37%) of whom received breast surgery alone

They then used the prognostic scoring system, described previously (Int J Radiat Oncol Biol Phys. 2006;65:1397-1403), to assign patients a score from 0 to 6, with 0 indicating the lowest risk for local recurrence and 6 indicating the highest risk.

Ten-year breast cancer mortality rates were lower with radiation than without (1.8% vs 2.1%; hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.62 - 0.88).

Patients with low prognostic scores — the majority of women with DCIS — derived no benefit from radiation therapy, according to Dr Golshan. There was no significant difference in breast cancer mortality, whether or not the women received radiation therapy, for those with a score of 0 (absolute difference, 20.4%; HR, 1.2; 95% CI, 0.67 - 2.06; P = .58) or a score of 1 (absolute difference, 20.5%; HR, 1.0; 95% CI, 0.70 - 1.47; P = .95).

In contrast, survival rates were significantly better for women who received radiation therapy than for those who did not when the prognostic score was 4 (absolute difference, 1.9%; HR, 0.31; 95% CI, 0.16 - 0.58; P < .001) or 5 (absolute difference, 4.0%; HR, 0.29; 95% CI, 0.09 - 0.91; P = .03).

Patients who might benefit from radiation include those with higher scores, those younger than 40 years, those with more than 4 cm of DCIS, and those with high-grade disease, Dr Golshan reported. Patients like these who received radiation had a 70% reduction in breast cancer mortality, although the absolute benefit was not great — 2% for those with a score of 4 and 4% for those with a score of 5.

For patients with a score of 4, the 10-year mortality rate was lower for patients who received radiation than for those who did not (1.3% vs 3.2%), he added.

Whether or not patients are prepared to undergo the risks and discomforts of radiation — 5.5 weeks of radiotherapy sessions (Monday through Friday), as well as potential lung and heart toxicity — for a 1.9% benefit is something they will need to discuss with their oncologists, he continued.

"Patients should know the pros and cons of different treatment options. What we are trying to do is make [the treatment decision] much more patient-centric, where patients and oncologists work together to come up with the best path of care," Dr Golshan emphasized.

"DCIS is a heterogeneous disease," he explained. We can now help stratify the potential benefits of radiation therapy and spare the patients who will not benefit, he added.

Dr Golshan reports serving in a consulting or advisory role for AbbVie. Dr Freedman reports receiving research funding from Genentech, Puma, and Eisai.

J Clin Oncol. Published online February 1, 2016. Abstract

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