A review of NCI's extramural grant portfolio: identifying opportunities for future research in genes and environment in cancer

Abstract

Background: Genetic and environmental factors jointly influence cancer risk. The NIH has made the study of gene-environment (GxE) interactions a research priority since the year 2000.

Methods: To assess the current status of GxE research in cancer, we analyzed the extramural grant portfolio of the National Cancer Institute (NCI) from Fiscal Years 2007 to 2009. Publications attributed to selected grants were also evaluated.

Results: From the 1,106 research grants identified in our portfolio analysis, a random sample of 450 grants (40%) was selected for data abstraction; of these, 147 (33%) were considered relevant. The most common cancer type was breast (20%, n = 29), followed by lymphoproliferative (10%, n = 14), colorectal (9%, n = 13), melanoma/other skin (9%, n = 13), and lung/upper aerodigestive tract (8%, n = 12) cancers. The majority of grants were studies of candidate genes (68%, n = 100) compared with genome-wide association studies (GWAS) (8%, n = 12). Approximately one-third studied environmental exposures categorized as energy balance (37%, n = 54) or drugs/treatment (29%, n = 43). From the 147 relevant grants, 108 publications classified as GxE or pharmacogenomic were identified. These publications were linked to 37 of the 147 grant applications (25%).

Conclusion: The findings from our portfolio analysis suggest that GxE studies are concentrated in specific areas. There is room for investments in other aspects of GxE research, including, but not limited to developing alternative approaches to exposure assessment, broadening the spectrum of cancer types investigated, and conducting GxE within GWAS.

Impact: This portfolio analysis provides a cross-sectional review of NCI support for GxE research in cancer.

Figure 1. Percentage of grants by cancer type from the 147 relevant grants

Frequency of cancer types and categories captured in portfolio analysis. This figure depicts the cancer types captured in the portfolio analysis and the frequency of each cancer type. The bars are labeled with the total number of grants that investigated each cancer type. The total number of grants is 147. Cancer types captured in the “other” category include brain, childhood cancers, endometrial, glioblastoma, liver, meningioma, osteosarcoma, renal, soft tissue carcinomas, and testicular. These cancers were grouped together because they had frequencies that were ≤ 2. The “multiple” category includes grants that examined more than one cancer type.

Figure 2. Percentage of grants by environmental exposure from the 147 relevant grants

Frequency of environmental exposures captured in portfolio analysis. Environmental exposure categories used in this portfolio analysis are listed and the bars are labeled with the number of grants that investigated each environmental exposure category. The total number of grants is 147, however, some grants investigated more than one environmental exposure and were counted more than once in the total for this specific figure.