Genetic Tests Can Predict Tumor Aggressiveness and Help Treatment Decisions

Specific genetic tests can help predict the prognosis in early-stage colon cancer patients and assist patients and physicians in making chemotherapy decisions.

Colon cancer treatment success often relies on how early the tumor is detected since early detection determines if the tumor can be removed surgically or if it responds to chemotherapy. Researchers have identified different genetic subtypes of malignant colon tumors that establish how the disease will develop. For example, up to 15% of malignant tumors consist of DNA repair mechanisms, also known as DNA mismatch repair deficiency (dMMR).

In a German study of 600 stage II colon cancer patients with locally aggressive tumors and without metastases, researchers used the metastasis-associated in colon cancer 1 (MACC1) gene biomarker in a genetic test that identified patients with defective repair mechanisms. Patients with low MACC1 gene expression received a prognosis consistent with patients with defective repair mechanisms—100% 5-year survival rate. This prognosis suggests that these patients would not benefit from chemotherapy.

"The blood test can indicate whether there is a higher risk of the tumor returning or metastasizing," Ulrike Stein, PhD, MD, the study leader, said in a press release. "It helps with the difficult decision of whether early-stage patients should receive chemotherapy.”

Only 15% of patients with high MACC1 are likely to reach a 5-year survival rate, while those with low levels have an 80% chance. Life expectancy is also greater for patients with dMMR tumors.

Overall, the 2 biomarkers—MACC1 and dMMR—can be used to predict how the disease will develop and the life expectancy for the patients. Treatment decisions and whether chemotherapy is required can also be established through these genetic tests.

“They recommend that, in the future, genetic test results should be combined with further genetic and epigenetic data from patients, ‘in order to understand the prognostic value of the complex molecular scenarios of early-stage colon cancer,’” the authors concluded.