The vast majority of patients will undergo surgery first for colon cancer if the tumour has not spread to other parts of the body. This is done with an intent to cure. After around a week, the histopathology (biopsy) report is in. Usually by this time the patient is discharged and doing well. The question now is whether chemotherapy is required or if observation with regular check-ups are enough. The basic rule of thumb is that chemotherapy is suggested if the chances of tumour recurrence is relatively high, based on scientific evidence.
Cutting to the chase, most patients in India will require chemotherapy since the stage at which the cancer is detected is usually rather advanced. Very early stage tumours are mainly detected on routine colonoscopy (general check-up without symptoms) so are incidentally diagnosed. Once a patient develops significant symptoms, it is usually at a stage which requires chemotherapy.
Specifically, patients with symptoms of significant obstruction (extreme difficulty or inability to pass stool) or severe bleeding, should receive chemotherapy. Patients in which the tumour has penetrated the wall of the colon or if lymph nodes are involved will require chemotherapy. Poorly differentiated tumours should also be considered for chemotherapy. If the report reveals stage 2 disease (pT3N0) with no other poor prognostic features, an MSI (Microsatellite Instability test) is advised. This helps in the decision about the benefit of adjuvant chemotherapy.
In short, there are instances when chemotherapy may not be required, but it is uncommon. Chemotherapy may not be advised if the tumour stage is very early, with minimal symptoms. Another reason for not advising chemotherapy is if the general condition of the patient is unfit to tolerate chemotherapy.
To conclude, your oncologist is the best person to decide treatment options in consultation with a multidisciplinary tumour board. Organ-based disease management clinical groups ensure best possible outcomes for patients.