Increased Risk of Second Cancers Following In Situ Breast Cancer

11% of women diagnosed with in situ breast cancer developed a non-breast cancer.

Increased Risk of Second Cancers Following In Situ Breast Cancer

by C.H. Weaver M.D. (05/2018)

According to the results of a study published in the British Journal of Cancer, women who have been diagnosed with in situ breast cancer (either DCIS or LCIS) have a higher risk of developing another cancer than women in the general population.

In situ breast cancer refers to non-invasive cancer that is confined to the breast ducts or lobules. Ductal carcinoma in situ (DCIS) is thought to be a precursor of invasive breast cancer. DCIS is frequently diagnosed with screening mammography that has detected small areas of calcification in the breast.

Patients rarely suspect they have breast cancer with this stage cancer. It is estimated that the average time to develop invasive breast cancer from DCIS is five to eight years. Lobular carcinoma in situ (LCIS) is thought to be an indicator for an increased risk of developing invasive breast cancer but may not be the direct precursor abnormality.

Women who have been diagnosed with invasive breast cancer are known to have an increased risk of developing a second cancer, particularly a second breast cancer, but less is known about the risk of second cancers among women with DCIS or LCIS.

To explore the risk of second cancers following a diagnosis of DCIS or LCIS, researchers evaluated information from a Dutch cancer registry. The researchers identified 1,276 women who had been diagnosed with DCIS or LCIS between 1972 and 2002. Most of these diagnoses (95%) were DCIS. The women were followed for an average of six years after diagnosis. The frequency of second cancers was compared to the expected frequency of cancer in the general population.

  • A second cancer (of any type) was diagnosed in 11% of the women. The risk of cancer in women with DCIS or LCIS was twice as high as the risk among women in the general population.
  • Women with DCIS or LCIS were at particularly high risk for developing a second breast cancer. The risk of breast cancer was more than three times higher among women with DCIS or LCIS than among women in the general population. An increased risk was observed for cancers in the same breast as the DCIS or LCIS, as well as for cancers in the opposite breast.
  • The risk of cancers other than breast cancer was 40% higher in women with DCIS or LCIS than in women in the general population.
  • The risk of a second cancer among women with DCIS or LCIS was similar to the risk of a second cancer among women with invasive breast cancer.

The researchers conclude that the risk of a second cancer following a diagnosis of DCIS or LCIS is similar to the risk among women with a diagnosis of invasive breast cancer and higher than the risk in the general population. The researchers note that closely watching for a second breast cancer (either in the same breast or the opposite breast) is particularly important.

Reference: Soerjomataram I, Louwman WJ, van der Sangen MJC, Roumen RMH, Coebergh JWW. Increased Risk of Second Malignancies after In Situ Breast Carcinoma in a Population-Based Registry. British Journal of Cancer. 2006;95:393-397.

Related News:Study Explores Frequency and Predictors of Invasive Breast Cancer in Women with DCIS or LCIS (5/15/2006)

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