CHICAGO — Ductal carcinoma in situ is associated with good long-term disease-specific survival, although the small percentage of tumors that do recur—particularly after radiotherapy—confers an increased risk of death.
The good outcomes were seen in two studies presented at the annual meeting of the American Society of Clinical Oncology. In a retrospective study of more than 50,000 women with ductal carcinoma in situ (DCIS) treated with total mastectomy or breast-conserving surgery plus radiation between 1988 and 2003, both treatments yielded similar 10-year disease-specific survival rates by Cox multivariate analysis, said Dr. Mohammed Nazir Ibrahim of Sligo General Hospital, Ireland.
The investigators analyzed the Surveillance, Epidemiology, and End Results (SEER) dataset of 543,261 individuals with invasive and noninvasive breast tumors.
Of these, 88,285 were in situ tumors; 33% of patients had total mastectomies and 30% had breast-conserving surgery (lumpectomy) with radiotherapy. Nearly all of the remaining patients had breast-conserving therapy only; 2.4% did not undergo surgery or radiotherapy, and 0.3% had radiotherapy only.
Women treated in the early part of the study were more likely to have total mastectomies, but breast-conserving surgery plus radiation became more common over time, he noted.
The analysis also revealed that the diagnosis of carcinoma in situ is increasing in the United States at a rate of 0.5% annually, Dr. Ibrahim said.
Tumor grade, ethnicity, and receptor status were found to be important prognostic factors in disease-specific survival.
Grade IV tumors had a hazard ratio (HR) of 1.7 compared with grade I tumors, African Americans had a more than twofold risk of death compared with Caucasians (HR 2.1), and hormone receptor-negative status likewise conferred a twofold increase in the risk of death (HR 2.2).
In another study, Dr. Irene Wapnir of the Stanford (Calif.) Comprehensive Cancer Center presented long-term outcomes after invasive breast tumor recurrence in women with primary DCIS in National Surgical Adjuvant Breast and Bowel Project trials B-17 and B-24.
The two trials included 2,612 women randomized between 1985 and 1994 to either lumpectomy alone or lumpectomy plus whole-breast irradiation (B-17), or to lumpectomy plus whole-breast irradiation with or without tamoxifen (B-24). The median follow-up was more than 12 years.
There were 336 deaths, 83 of which were from breast cancer. However, the breast cancer deaths included deaths that were potentially due to contralateral breast cancers, Dr. Wapnir said.
Breast cancer-specific survival ranged from 96% to 98%, and patients receiving lumpectomy, radiation, and tamoxifen had the best survival.
Adding radiation therapy reduced the risk of an invasive breast tumor recurrence by 59%, and adding tamoxifen to lumpectomy plus radiation further reduced the risk of an invasive breast cancer recurrence, Dr. Wapnir said.
Although overall mortality was low, the subsequent recurrence of an invasive breast tumor doubled the risk of death. Mortality risk was even higher for women who received lumpectomy plus whole-breast irradiation, Dr. Wapnir said. (See chart, below right.)
Among 242 cases of invasive breast tumor recurrence, there were 35 deaths, 22 of which were breast cancer-related. Of these deaths, 9 occurred in the lumpectomy-alone patients, 21 in the lumpectomy plus radiation patients, and 5 in the lumpectomy plus radiation plus tamoxifen patients. (See chart, below left.)
Although the recurrence of invasive breast tumor is the most common first-failure event in lumpectomy-treated patients with DCIS, overall breast cancer-specific mortality for all treatment modalities in the two trials is low, Dr. Wapnir concluded.
ELSEVIER GLOBAL MEDICAL NEWS
ELSEVIER GLOBAL MEDICAL NEWS