A clinico-pathological study on cancer in sclerosing adenosis

Cancer in sclerosing adenosis includes the following 2 types: cancer genuinely arising from sclerosing adenosis and cancer arising near a sclerosing adenosis lesion and infiltrating into it. This study aimed to elucidate the features of the former by comparing both types.

This study included 28 lesions in 27 cases of cancer in sclerosing adenosis for which surgery was performed during a 2-year period from January 2006 at the Cancer Institute Hospital of the Japanese Foundation for Cancer Research. We determined the proportions of cancer in sclerosing adenosis relative to the overall lesion of ductal carcinoma in situ. They were compared for 13 clinico-pathological factors by dividing the lesions into 2 groups: those involving cancer in 50 % or more (cancer in sclerosing adenosis predominant type-inner type) and those involving cancer in less than 50 % (cancer out of sclerosing adenosis predominant type-outer type).

There were 20 lesions (71 %) of the inner type and 8 lesions (29 %) of the outer type. The comparison between the 2 types revealed significant differences in the following 3 factors. Bilateral breast cancer was observed in 5 cases (26 %) of the inner type and in none (0 %) of the outer type, indicating that there were significantly more cases of bilateral breast cancer for the inner type (p = 0.04). Regarding the subtypes of ductal carcinoma in situ, there were significantly more cases of the non-comedo type for the inner type (p = 0.002). Significantly fewer cases were positive for human epidermal growth factor receptor type 2 (HER2) for the inner type (p = 0.007).

The results of this study suggest that cancer genuinely arising in sclerosing adenosis may often have biological features of bilateral breast cancer, non-comedo type in subtype, and being negative for HER2.