Recurrence after Dcis and Stage I Breast Cancer

Ductal carcinoma in situ (dcis) is often described as a noninvasive form of breast cancer or a precursor lesion1. This designation is based on the histologic appearance of the lesions and on their typical clinical course. In strict terms, “noninvasive” refers to the absence of visible cancer cells beyond the basement membrane (pathology description of a lesion once it is removed and examined under the microscope). The term “noninvasive” is misleading if it is used to imply that the lesions do not have intrinsic invasive potential. The existence of dcis with microinvasion (less than 1 mm) attests to the potential for invasion, at least for some patients. It is a matter of ongoing interest if dcis with microinvasion should be classified with dcis, with invasive cancer, or as part of a continuum. Further, if the invasive component exceeds 1 mm, the lesion is called “invasive breast cancer with accompanying dcis.” Some cases of dcis are diagnosed concurrently with invasive cancer, and other cases of dcis are followed by an invasive breast cancer in the same breast. The subsequent diagnosis of an invasive or noninvasive cancer in the same breast is termed an in-breast “recurrence” even though the new lesion might represent a re-emergence of cancer cells that were present in the breast at the time of excision or an independent second primary cancer. Here, we use “inbreast recurrence” in that dual sense. The incidence of in-breast recurrence at 10 years after dcis is approximately 20%2,3; specifically, 20% is the actuarial risk of recurrence after surgical excision. The incidence of recurrence in the absence of surgical intervention— that is, under “watchful waiting”—is expected to be higher. A proposed nonsurgical expectant approach to dcis management is controversial4,5. Most cases of dcis are diagnosed through mammography5, and most are small and nonpalpable at ABSTRACT