It is well known that certain type of nonmalignant lesions predispose patients to increased risk of developing breast cancer.
Lobular Carcinoma In Situ - Despite the name is not Cancer but indicates 25% risk of developing Breast Cancer over 25 years in either Breast. They can be difficult to find by imaging or exam.
Atypical Hyperplasia (ductal or lobular) - These are also pre-cancerous lesions. Recently NSABP P-1 study showed increased risk of invasive breast cancer in these patients by 57%.(10.11 vs. 6.44 invasive Breast Cancer events per1000 patients with Atypical Hyperplasia or without it at about four years).
LCIS & Atypical Hyperplasia lesions are often diagnosed on core biopsy. They are often found associated with invasive cancers and DCIS in up to 35% cases when examined carefully in generous excisions. These diagnosis therefore require excision to exclude invasive cancer co-existing. These lesions by them selves do not need clear margin or radiation if no cancer is found.
Ductal Carcinoma in Situ is non invasive cancer and does need excision with clear margin. Radiation is usually recommended and recent trial showed that at 10 years it reduced risk of local recurrence of cancer by 42%. Local recurrence rate of 1% per year is noted. Careful pathological evaluation is needed for occult invasive Cancer and clear margin. Up to 10mm margins have been recommended in some of recent reviews as margins can be difficult and misleading in these lesions. With careful management survival of nearly 100% can be achieved.
Cancer prevention with Tamoxifen is recommended in these high risk individuals as it has shown to reduce risk of invasive Breast Cancer by 56% in patients with DCIS & LCIS and by 86% in patients with Atypical Hyperplasia. Prevention trials in post-menopausal women showed that Evista (Raloxifen) was equally effective in decreasing risk of invasive Cancer although somewhat less effective in reducing risk of in Situ Cancer. Evista may be safer option in some patients.
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