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Value of Routine Radiotherapy Confirmed in Ductal Carcinoma


 

SAN ANTONIO — Radiotherapy as part of breast-conserving treatment for patients with ductal carcinoma in situ reduced the 10-year risk of local recurrence by 47% in a large European randomized trial, Dr. Nina Bijker reported at a breast cancer symposium sponsored by the Cancer Therapy and Research Center.

For this reason, whole-breast radiation therapy remains the standard of care in women with ductal carcinoma in situ (DCIS), despite its problematic side effects and inconvenience, added Dr. Bijker of the Netherlands Cancer Institute, Amsterdam.

The sole patient subgroup in the European Organization for Research and Treatment of Cancer (EORTC) trial 10853 who were found to have a low risk of recurrence without radiotherapy was a small one: women over age 40 years with well-differentiated micropapillary or clinging-type DCIS lesions.

“In those lesions you could consider omitting radiotherapy. But that was the only group of patients that had a much lower risk of local recurrence. The cribriform lesions did as badly as the solid or comedo lesions,” she added.

Dr. Bijker reported on 1,010 patients with DCIS who underwent local excision and randomization to no radiation or to 50 Gy of whole-breast radiotherapy delivered in 25 fractions. At a median 10.5 years' follow-up, the radiotherapy group had an 85% rate of freedom from local recurrence, compared with 74% in controls. The magnitude of risk reduction with radiotherapy was similar for invasive recurrence and recurrent DCIS. However, there was no difference between the radiotherapy group and controls in terms of overall survival or the incidence of contralateral breast cancer.

Women aged 40 years or younger at diagnosis of DCIS had a dramatically increased risk of local recurrence: 34% at 10.5 years, compared with 19% in women beyond age 40.

The causes of this strong age effect are unclear, since younger and older patients had similar rates of poorly differentiated DCIS lesions as well as excision without free margins. The local recurrence rate in women age 40 or younger at the time of breast-conserving therapy was 23% with radiotherapy and 43% without it.

Among patients whose margins were not specifically reported free of tumor following local excision, the local recurrence rate was 39% among controls and a still substantial 24% in those who got radiotherapy.

“This indicates that radiotherapy does not compensate for involved margins,” Dr. Bijker observed.

Women aged 40 or younger at diagnosis of DCIS had a dramatically increased risk of local recurrence. DR. BIJKER

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