BOSTONNeither the presence nor the extent of lobular carcinoma insitu (LCIS) is related to risk of local recurrence in patients with invasivebreast cancer treated with conservative surgery and radiotherapy, a retrospectivestudy from the Joint Center for Radiation Therapy has shown.
"This is very different from the situation with associated DCIS,"Stuart Schnitt, MD, said at a general session. Joint Center data show thatinfiltrating ductal carcinoma with a large amount of associated DCIS hasa five-year local recurrence rate of 24% vs 6% when there is little orno DCIS.
The LCIS study included 858 patients with clinical stage I or II infiltratingductal carcinoma (782 patients), infiltrating lobular carcinoma (44 patients),or infiltrating carcinoma with mixed ductal and lobular features (32 patients),treated with conservative surgery and radiotherapy.
Overall, neither local recurrence nor the incidence of distant failurewas related to histologic type. In terms of LCIS, 4% of patients with infiltratingductal cancer had associated LCIS. Not surprisingly, the vast majority(93%) of patients with infiltrating lobular carcinoma had associated LCIS.Of the patients with mixed ductal/lobular features, 59% had associatedLCIS.
Other prognostic factors for local recurrence were equally distributedamong the three groups and among those with and without LCIS. The mostimportant prognostic factor, margin status, was unknown in most patients.
The investigators then looked at the 10-year crude rate of local recurrenceamong patients with and without LCIS. Patients with infiltrating ductalcarcinoma and no LCIS had a local recurrence rate of 14% vs 10% for thosefew patients in whom LCIS was present. Among infiltrating lobular carcinomas,there were no local recurrences in the three patients without LCIS, andfive (12%) among the patients with LCIS.
For patients with mixed features, local recurrence was 15% with no LCIS,and 16% with LCIS. None of these differences were significant. Similarly,the extent of LCIS was not associated with the risk of local recurrencein any group. Based on these results, Dr. Schnitt suggests that the presenceof associated LCIS should not influence local management of infiltratingductal, lobular, or mixed carcinoma.