Senior Director, Surgical Oncology, Fortis Hospital, Vasant Kunj, New Delhi
Part 8 of 10 in When to Suspect Cancer and How to Refer
Bowel Habit Changes and Colorectal Cancer: Colonoscopy Screening Guidelines
January 25, 2026
Changes in bowel habit or rectal bleeding are common presenting complaints, and Dr. Shubham Jain sets out the warning signs that separate a benign cause from one that needs urgent evaluation.
Upper and lower gastrointestinal warning signs
Warning signs for upper gastrointestinal cancers include difficulty swallowing, blood in vomit or stool, upper abdominal masses, involuntary weight loss, anaemia associated with upper abdominal pain, and persistent reflux symptoms not relieved by medication and antacids, especially with jaundice. For patients over 40, he also flags persistent bleeding after successful treatment of haemorrhoids, changes in bowel habit, constipation or diarrhoea, progressive abdominal pain, unexplained weight loss, abdominal masses, anaemia requiring transfusion, or a significant family history.
Colonoscopy screening guidelines
Colonoscopy is recommended starting at age 45 and continuing to age 75, or until life expectancy falls below 10 years. High-risk individuals can be offered colonoscopy earlier than 45, or screened every one to three years. Patients unwilling to undergo colonoscopy can be offered stool-based tests or a visual exam such as flexible sigmoidoscopy instead.
This article is based on a Jivo Masterclass session conducted by Dr. Shubham Jain, Senior Director, Surgical Oncology, Fortis Hospital, Vasant Kunj, New Delhi. The article has been summarised with the assistance of an AI tool from the original masterclass recording. Watch the full Masterclass recording
Looking for a diagnosis or treatment for colorectal cancer? Get in touch with the Jivo team
This guide is based on a live Jivo Masterclass — Dr. Shubham Jain taught doctors across Africa on January 25, 2026.
FROM THE LIVE Q&A
Dr. Alem (Ethiopia)
How do we approach cancer of unknown primary with only liver metastases or oligometastases?
Dr. Shubham Jain
This is a tricky situation where metastatic deposits are seen without knowing where they are coming from. A PET scan is needed to confirm there is no other site of disease in the body, and immunohistochemistry on the biopsy can give clues to where the cancer is arising from, guiding directed and targeted imaging afterward. Many times the primary is never found. If there are only liver metastases, treatment starts with a palliative intent, and depending on how the patient responds and their performance status, a curative approach involving surgery may later be attempted, though nothing can be assured to the patient in advance.
Frequently Asked Questions
What is your take on mebendazole and ivermectin as adjunct tablets for cancer treatment?▼
These are being evaluated as adjuvant therapy for cancer, but there is not yet sufficient scientific data backing them, so standard chemotherapy remains the primary reliance. What is showing real results is targeted therapy and immunotherapy, where survival has improved and recurrences and side effects have reduced. Cost has been a sore point since these are expensive medicines, but with generic versions now available and patient assistance programmes extending to international patients, these costs are coming down.
How do you see complications from radiotherapy on the left side of the chest?▼
The most common complication with radiotherapy for left-sided breast cancers is cardiotoxicity. Radiation oncologists manage this with deep inspiratory breath-hold and gating techniques, training the patient to hold their breath during the active phase of radiotherapy so toxicity to the heart is reduced, chest wall motion is reduced, and radiation is delivered accurately to the target volume. More precise machines such as IGRT and 4D-CRT are also improving precision for left-sided breast and chest wall tumours.
Which cancers have patient assistance programmes, and how do they work, and who is eligible?▼
Until very recently, patient assistance programmes for targeted therapy and immunotherapy were only available to Indian patients. Because these drugs are costly, companies assist with procuring them at up to a half or a third of the usual cost, which is out of reach for many domestic Indian patients too because of regulations. These regulations are now relaxing, and more international patients are able to receive the benefit of these programmes.
On the slide about smokers, it said 20 packs. Does that mean 20 packs smoked per day?▼
Not 20 packs per day, that would be 400 cigarettes a day, which is not possible. Pack-years is the number of packs smoked per day multiplied by the number of years smoked. Two packs a day for ten years makes 20 pack-years, as does one pack a day for twenty years, or half a pack a day for forty years.
How should a doctor practising in a resource-constrained setting, without enough diagnostic facilities to screen large populations, know which symptoms genuinely warrant referral and which could be a false alarm?▼
Any suspected cancer requires resources for investigation and treatment, so it should be evaluated at a good high-volume centre that gives the best chance of cure. It is difficult to assess the outcome or treatment at an initial stage, so the primary reliance has to be on the clinical signs and symptoms already discussed, which are the basis for suggesting a patient be evaluated at a high-volume centre.
At what age should colonoscopy screening for colorectal cancer start?▼
Age 45, continuing to age 75 or until life expectancy falls below 10 years. High-risk individuals can start earlier or be screened every one to three years.
What alternatives exist for patients unwilling to have a colonoscopy?▼
Stool-based tests or a visual exam such as flexible sigmoidoscopy can be offered instead.
In This Series: When to Suspect Cancer and How to Refer
- 1.When to Suspect Cancer and How to Refer
- 2.Breast Lump Assessment: Why Triple Assessment Comes Before a Diagnosis
- 3.Breast Cancer Screening: Mammography Guidelines and How to Prepare Patients
- 4.Persistent Hoarseness and Laryngeal Cancer: Warning Signs and Voice Rehabilitation
- 5.Persistent Cough and Lung Cancer: Warning Signs and Low-Dose CT Screening
- 6.Abdominal Bloating and Ovarian Cancer: Warning Signs and the Role of CA-125
- 7.Abnormal Vaginal Bleeding: Endometrial Cancer, Cervical Cancer and HPV Vaccination
- 8.Bowel Habit Changes and Colorectal Cancer: Colonoscopy Screening Guidelines
- 9.Common Myths About Cancer Diagnosis and Treatment
- 10.Cancer of Unknown Primary: How Doctors Find the Source