Evaluating Immunoscore as a prognostic factor in stage 3 colon cancer

This study investigated Immunoscore (IMS) as a prognostic tool in patients with stage 3 colon cancer. Researchers suggested that a high IMS is associated with prolonged survival in these patients.

Colorectal cancer is the third most common cancer worldwide. A significant percentage of patients present with high-risk cancer at diagnosis.

Chemotherapy is recommended for stage 3 colon cancer. However, prior studies showed that only 62 to 64% of these patients receive chemotherapy. Additionally, only 20% of patients benefit from chemotherapy after surgery. This suggests that 80% of patients are exposed to unnecessary treatments and side effects. Testing patients for specific risk factors detects the patients who would benefit from chemotherapy.

Prior studies suggested that colon tumors with infiltrated immune cells are associated with better outcomes. This was suggested to be a useful predictive factor. The IMS is a method to assess cancer prognosis, based on the immune cells infiltrating the tumor. The effectiveness of IMS has been shown for stage 1 to 3 cancers and stage 2 colon cancer. However, its effectiveness in patients with stage 3 colon cancer is still not clear.   

This study included information about 763 patients with stage 3 colon cancer. Patients from the USA and Canada were assigned to group 1 and patients from Europe and Asia to group 2. IMS was defined as low (0-25%), medium (over 25% to 70%), or high (over 70% to 100%).

Time to recurrence (TTR; time from treatment to recurrence – when cancer comes back), overall survival (OS; time from treatment to death by any cause), and disease-free survival (DFS; time from treatment to progression) were assessed. Microsatellite stable status (MSS) was also assessed as well as the effectiveness of chemotherapy. MSS measures the mutation (permanent change in the gene) rate of the tumor.

Patients with a high IMS presented a lower risk of recurrence, in both groups. Patients with a high IMS had a 52% improvement in the odds of a better recurrence-free rate at 3 years compared to a low IMS. These patients also showed an association with prolonged TTR, OS, and DFS.

IMS association with TTR was independent of other factors such as sex and tumor stage. Patients with high IMS had a 59% improvement in the odds of a better TTR. In MSS patients, a high IMS was associated with prolonged TTR. These patients had a 64% improvement in the odds of a better TTR.

In low-risk patients with high IMS, chemotherapy was associated with a 58% improvement in the odds of a better survival, when compared to no chemotherapy. In high-risk patients, this percentage was 50%, when compared to low IMS.

This study concluded that high IMS is associated with prolonged survival in stage 3 colon cancer. The authors suggested that patients with a high IMS can benefit the most from chemotherapy.

This study included a diverse patient population from 13 different countries. The differences in patient-care practices between the different countries could have affected the results.