The impact of family history in patients with in situ breast cancer

This study examined the influence of family history on the risk of developing invasive breast cancer in women with in situ breast cancer. The authors determined that family history increased the risk of developing invasive breast cancer in these women.

In situ breast cancer is breast cancer that does not spread into the surrounding tissue. Even after treatment, women with in situ breast cancer are at risk of developing invasive breast cancer. Invasive breast cancer is cancer that has invaded the surrounding normal tissue. A number of factors play a role in this risk, such as differences in treatment. Whether or not family history plays a role is not clear.

This study examined how a family history of breast cancer can affect the risk of developing invasive breast cancer. This study included information from 8,111 patients with in situ breast cancer included in a cancer registry. Family history of breast cancer was defined as having at least one first-degree relative (such as a mother) with invasive breast cancer.

Patients with a family history of breast cancer were 50% more likely to develop invasive breast cancer in the other breast. The risk of invasive cancer was almost doubled in patients who were diagnosed with breast cancer under the age of 40 compared to those over 40. The risk of invasive cancer in women under 40 with a family history of breast cancer was 14 times higher when compared to the general population. 

The overall mortality risk was higher in women with in situ breast cancer. This was dependent, though, on the development of invasive cancer.

This study concluded that women with in situ breast cancer and a family history of breast cancer were at a higher risk of developing invasive cancer in the other breast.

The authors have no information on the type of cancer, the way it was detected or the treatment that was used. The cases of new in situ cancers in the same breast are not reported in the study. The estimated risks only assume that one breast is at risk from subsequent invasive cancer. Only women with breast cancer were included in the study.

Discuss any family history of breast cancer with your doctor.