Prostate cancer is the most common male cancer in the developed world, with about 1 in every 7 men being diagnosed throughout their lifetime.
Radiotherapy is one of the main treatments for prostate cancer, using CT scans and MRIs to map out the location of the tumor cells, and X-rays to target the affected areas. However, this type of treatment often results in clinically relevant side effects in up to 40% of patients in the short term, and 7.7% of patients in the longer term.
There has been growing evidence for a role of genetic variants in the development of radiation-induced toxicity. For example, a recent study identified common genetic variants associated with late radiotherapy toxicity by analyzing single nucleotide polymorphisms in 1,850 patients who had received either adjuvant breast radiotherapy or radical prostate radiotherapy.
Previous research was unable to identify the common genetic variation behind this phenotype.
In a recent study published in Nature Genetics, a team of researchers found that patients who present variations in the TANC1 gene have an increased risk of late radiation-induced damage.
In this study, the scientists performed a genome-wide association analysis on a Spanish cohort of 741 individuals with prostate cancer treated with external beam radiotherapy along with replication cohorts of 633 cases from the U.K. and 368 cases from North America.
They found that one locus in chromosome 2 comprising TANC1 was replicated in the second stage, which alongside the fact that this gene plays a role in regenerating damaged muscle, suggested TANC1 as the susceptibility locus for late radiotherapy-induced toxicity.
The results from this study can help build a predictive genomic test, in which patients suffering from prostate cancer could receive adequate personalized treatment, depending on their genomic variants. The long-term side effects currently associated with radiotherapy can reduce patients’ quality of life and also limit the intensity of treatment, minimizing the capacity to control tumor growth. Personalized treatment would allow stronger radiotherapy for patients who displayed a suitable genetic profile and alternative options, such as chemotherapy, for patients who did not.
Catherine West, Professor of Radiation at the University of Manchester and lead researcher in this study said that the paper was “an exciting first step” but cautioned that more work was needed, “we now need to study perhaps 50,000 patients to identify enough genetic variants for a test that can be used clinically.”