Germline genetic testing registers low numbers

The adoption rate of germline genetic testing among individuals diagnosed with cancer in some states in the US over a period of 6 years remains subpar, with only 6.8 percent undergoing testing, as reported in a study.

The study used data from the Surveillance, Epidemiology, and End Results registries in California and Georgia. Researchers identified a total of 1,369,602 patients at least 20 years of age who had been diagnosed with any type of cancer between 1 January 2013 and 31 March 2019.

Cancer types included male breast (50 percent), ovarian (38.6 percent), female breast (26 percent), multiple (7.5 percent), endometrial (6.4 percent), pancreatic (5.6 percent), colorectal (5.6 percent), prostate (1.1 percent), and lung (0.3 percent).

Germline genetic testing within 2 years of a cancer diagnosis, the primary study outcome, was performed for 93,052 (6.8 percent) patients. Testing rates increased over time, especially among those with pancreatic cancer, from 1.2 percent in 2013 to 18.6 percent in 2019. Testing remained low throughout among patients with lung cancer, from 0.1 percent in 2013 to 0.8 percent in 2019.

Testing trends according to logistic regression showed that genetic germline testing rates were significantly lower among Asian (22 percent), Black (25 percent), and Hispanic (23 percent) patients than among non-Hispanic White (31 percent) patients (p<0.001).

Of the variants showed in the pathogenic results, between 67.5 percent and 94.9 percent were identified in genes for which practice guidelines recommend testing and between 68.3 percent to 83.8 percent were identified in genes associated with the diagnosed cancer type.

Given the mounting evidence supporting germline-directed cancer screening, preventive surgery, and targeted therapies in improving survival, the low rates of germline genetic testing may contribute to higher rates of cancer mortality, according to the researchers. [Ann Oncol 2022;33:1250-1268; N Engl J Med 2020;383:2345-2357; JAMA 2010;304:967-975; Ann Intern Med 2011;155:69-79]