SAN ANTONIO — Lobular carcinoma in situ is not always the indolent disease it has long been considered to be, Dr. Bruno Cutuli said at a breast cancer symposium sponsored by the Cancer Therapy and Research Center.
Nor is lobular carcinoma in situ (LCIS) simply a risk factor for invasive breast cancer, as has been the traditional view. In fact, some LCIS lesions are precursors of invasive breast cancer—and as such, may warrant more aggressive local therapy, such as whole-breast radiotherapy following surgical excision, said Dr. Cutuli, a radiation oncologist at the Courlancy Polyclinic, Reims, France.
LCIS accounts for 1%–2% of all breast cancers and 15%–20% of all in situ carcinomas. The age-specific incidence reportedly jumped 2.6-fold between 1980 and 2001, for two likely reasons.
One is increased mammographic screening. Although LCIS isn't usually visible on mammography, it is often discovered on biopsy of a cyst, fibroadenoma, or other mammographically detected abnormality.
The other factor involved in the steep rise in LCIS since 1980 was probably the widespread use of hormone therapy, according to Dr. Cutuli.
Dr. Cutuli presented a retrospective study of 330 cases of pure LCIS in 325 patients treated during 1985–2000 at 12 French cancer centers. The patients' median age was 49 years, and 35% were postmenopausal. A first- or second-degree family history of breast cancer was present in 29%. In 24% there was prior benign breast disease.
Local recurrence rates following various therapies were illuminating. Lumpectomy was undergone by 77%; these patients had a 19.2% ipsilateral local recurrence rate during a median follow-up of 8.2 years. Of particular concern was that 60% of these local recurrences were invasive. This experience translated to a 10-year ipsilateral local recurrence rate of 24% following conservative surgery, with a median 4.4-year delay between surgery and diagnosis of recurrent disease.
Among the 11% of patients with LCIS treated via conservative surgery plus radiotherapy, the ipsilateral local recurrence rate was 5.4% during a median 12.4 years of follow-up. Mastectomy-treated patients had no ipsilateral local recurrences. The contralateral breast cancer rate was 7.8% in patients treated with breast-conserving surgery, 5% in those who got surgery plus radiation, and 10% following mastectomy.
This was not a randomized trial. At present no well-defined criteria exist as to which LCIS subtypes are more aggressive and thus likely to benefit from radiotherapy. But the current thinking is that the subtypes most prone to local recurrence include extensive LCIS with more than 10 involved lobules, LCIS with necrosis, pleomorphic tumors, and lesions containing cells with large nuclei, Dr. Cutuli said.
He added that his own favorable experience with breast-conserving surgery and whole-breast radiotherapy in 25 LCIS patients—there was only a single local recurrence in 12 years of follow-up—has convinced him this is a therapeutic approach worth testing in randomized trials.