Although breast cancer has not traditionally been considered one of the cancers associated with Lynch syndrome, evidence is building that there might be a link.
Breast cancer may actually be with in the spectrum of Lynch cancers.
An Australian team reviewing the pathology of breast cancers in women who carried a mutation for Lynch syndrome ( hereditary non-polyposis colon cancer) found that half of the breast tumors were mismatch repair deficient — a hallmark of Lynch cancers.
The team found 107 cases of breast cancer and 90 families in the Colorectal Cancer Family Registry where
- both breast and colon cancer co-occurred
- families met either modified Amsterdam criteria, or had at least one colorectal cancer occurring before age 50
- breast tissue was available in the tissue bank for mismatch repair (MMR) testing
Among those breast cancers, 35 women with a Lynch mutation had been diagnosed with breast cancer. Of these, 18 (51%) showed deficient mismatch repair and immunohistochemical testing found proteins missing that were the same as the family mutation.
Michael D. Walsh from the Familial Cancer Laboratory at the Bancroft Centre in Queensland, Australia, wrote,
Mismatch repair deficiency was identified in 51% of breast cancers arising in known mutation carriers. Breast cancer therefore may represent a valid tissue option for the detection of MMR deficiency in which spectrum tumors are lacking.
SOURCE: Walsh et al. , Clinical Cancer Research, Volume 16, Number 7, April 1,2010.