A study published in Nature Communications has shed light on the hereditary elements of 12 cancer types.
Investigators looked for rare germline mutations in genes known to be associated with cancer and found the frequency of these mutations varied widely, from 4% in the acute myeloid leukemia (AML) cases studied to 19% in cases of ovarian cancer.
The team’s analysis also revealed an unexpected inherited component to stomach cancer and provided some clarity on the consequences of certain mutations in the BRCA1 and BRCA2 genes.
Li Ding, PhD, of Washington University School of Medicine in St Louis, Missouri, and her colleagues conducted this study, analyzing genetic information from more than 4000 cancer cases included in The Cancer Genome Atlas project.
“In general, we have known that ovarian and breast cancers have a significant inherited component, and others, such as acute myeloid leukemia and lung cancer, have a much smaller inherited genetic contribution,” Dr Ding said. “But this is the first time, on a large scale, that we’ve been able to pinpoint gene culprits or even the actual mutations responsible for cancer susceptibility.”
To help tease out cancer’s inherited components, Dr Ding and her colleagues looked for germline truncations in 114 genes known to be associated with cancer.
“We looked for germline mutations in the tumor, but it was not enough for the mutations simply to be present,” Dr Ding said. “They needed to be enriched in the tumor—present at higher frequency. If a mutation is present in the germline and amplified in the tumor, there is a high likelihood it is playing a role in the cancer.”
The investigators found germline truncations in all 12 cancer types analyzed, but the mutations occurred in varying frequencies depending on the cancer.
The percentage of tumors with truncations in the germline was 4% for AML and glioblastoma; 5% for kidney cancer; 7% for lung adenocarcinoma and endometrial cancer; 8% for head and neck cancer, glioma, lung squamous cell carcinoma, and prostate cancer; 9% for breast cancer; 11% for stomach cancer; and 19% for ovarian cancer.
“We also found a significant number of germline truncations in the BRCA1 and BRCA2 genes present in tumor types other than breast cancer, including stomach and prostate cancers, for example,” Dr Ding said. “This suggests we should pay attention to the potential involvement of these 2 genes in other cancer types.”
The investigators said they identified 13 cancer genes with significant enrichment of rare truncations. Some of these were associated with specific cancers—for example, RAD51C in AML, PALB2 in stomach cancer, and MSH6 in endometrial cancer.
And the team observed significant, tumor-specific loss of heterozygosity in 9 genes—ATM, BAP1, BRCA1/2, BRIP1, FANCM, PALB2, and RAD51C/D.
Dr Ding said more research is needed to confirm these results before they can be used to advise patients making healthcare decisions.
“Our strategy of investigating germline-tumor interactions provides a good way to prioritize important mutations that we should focus on,” she said. “For the information to eventually be used in the clinic, we will need to perform this type of analysis on even larger numbers of patients.”
