Diagnosis and Detection of Cancer

Early detection of cancer rests on three habits that any primary physician can build into routine practice: recognising the seven warning signs, screening healthy people before symptoms appear, and confirming every suspicion with a biopsy before treatment begins. Cancer found at an early stage can be cured, which is why the first doctor a patient sees carries so much of the outcome.

That is the case made by Dr. Mohit Agarwal, Principal Director & Head Medical Oncology, Fortis Hospital, Shalimar Bagh, New Delhi, India, in a Jivo Masterclass for international doctors in May 2024. He built the session around the questions patients put to the physician they consult first when cancer is suspected, distilled from 20 years of clinical practice. His starting point was blunt. Cancer, he said, is a scary word.

This guide covers the core of his framework: who develops cancer, the warning signs that should prompt investigation, the role of screening and vaccination, and why he insists that cancer is not a death sentence. Three companion articles go deeper:

• Cancer Risk Factors: Smoking, Family History and Diet covers inherited risk, genetic testing, tobacco and nutrition.
• Can Tumour Markers Screen for Cancer? Biopsy and Staging explains how a suspicion becomes a staged diagnosis.
• Can Chemotherapy and Hormone Therapy Be Given Together? covers chemotherapy, targeted therapy, immunotherapy and the order in which they are given.

Who can develop cancer

Cancer can affect any person, of any gender, race or age. Dr. Agarwal opens with this because the most common belief he meets in clinic runs the other way: patients who have never been ill and never needed medicine assume they are protected. Fitness lowers the probability. It does not rule cancer out, and a physician who accepts a patient's clean medical history as reassurance may miss an early presentation.

The second belief he confronts is that a family history is needed before cancer can be considered. Only 5 to 10 per cent of cancers are caused by an inherited gene mutation, and most people diagnosed have no strong family history of the disease. The practical lesson for a referring doctor is that the absence of a family history should never lower the index of suspicion. The full discussion of inherited risk and when genetic testing is indicated sits in the risk factors article.

Cancer is not one disease

Dr. Agarwal's central slide made a simple point with wide consequences: cancer is not one disease. It differs according to the organ in which it starts, so two patients with cancer will not behave the same way. Each will have a different treatment, a different outcome and a different cure rate.

This answers a question families ask constantly. A relative or neighbour was cured without surgery, so why is surgery, chemotherapy or radiation being insisted upon now? The answer is that treatment is chosen for the specific cancer a patient has, not for cancer in general. Comparing one patient's pathway with another's is rarely meaningful.

The seven warning signs of cancer

The seven warning signs of cancer are the most practical tool a primary physician has for early detection. Dr. Agarwal presented them as signals that doctors themselves will meet in practice:

1. A change in bowel or bladder habits, such as persistent constipation, diarrhoea or difficulty passing urine.
2. A sore or ulcer that does not heal.
3. Unusual bleeding or discharge from any site in the body.
4. Thickening or a lump in the breast or elsewhere in the body.
5. Difficulty in swallowing.
6. An obvious change in a wart or mole.
7. A nagging cough or hoarseness, which in his view warrants attention when it persists for more than four weeks.

None of these signs proves cancer. Each is a reason to examine, investigate and, where the explanation is not clear, refer. A symptom-by-symptom version of these signs, organised by cancer type, is in Cancer Warning Signs: When to Suspect Cancer by Type. Asked during the session how cancer diagnosis can be brought closer to patients in their own communities, Dr. Agarwal answered that it happens only through education and awareness: people who notice any of the seven signs need to talk to their doctor, undergo screening and seek a consultation early, so that cancer is diagnosed and treated early.

How a suspicion becomes a diagnosis

A suspicion of cancer is confirmed only by a biopsy, the removal of a small sample of tissue for examination under the microscope. Dr. Agarwal addressed the most persistent fear directly: the risk that a biopsy spreads cancer is very small. Modern biopsies are precise. His example was a CT-guided lung biopsy, in which the needle is steered by scan images into the centre of the mass.

He made two further points that matter to the doctor ordering the first tests. Normal blood counts, kidney tests and liver tests do not exclude cancer, because many cancers leave them untouched. And although treatment should start promptly, it should not start until the disease has been staged and its nature established on biopsy. These steps, together with the limited role of tumour markers, are covered in detail in Can Tumour Markers Screen for Cancer? Biopsy and Staging.

The four stages of cancer

Every cancer is described in four stages. In Dr. Agarwal's framing, stages one to three represent disease that is still local or regional, and patients at these stages can be cured. Even at stage four, selected patients can be cured completely. Stage is one of the main facts that shape a treatment plan, which is why early detection changes outcomes so sharply.

Early detection of cancer through screening

Cancer screening is testing for people who feel well, not for patients. Dr. Agarwal drew the distinction carefully: the purpose of screening is to find the disease in an asymptomatic individual, at a very early stage, so that it can be cured. He set out the main programmes:

• Mammography is an X-ray of the breast. His recommendation is that every woman over 40 has one every year, because it detects breast cancer at a very early stage.
• The Pap smear is a simple test for cervical cancer, which he recommends for every woman from the age of 21.
• Prostate and lung cancer also have established screening protocols for people at expected risk. Lung cancer screening uses low-dose CT in adults aged 50 to 80 with a heavy smoking history, and testing for prostate-specific antigen (PSA), a protein measured in the blood, is generally an individual decision for men between 55 and 69.

Screening is a habit for healthy people, and a primary physician is usually the only clinician in a position to recommend it before symptoms appear. Age-by-age schedules for each programme are set out in Cancer Screening Guidelines: Mammography to Colonoscopy.

The HPV vaccine and cervical cancer

Patients often ask whether a cancer vaccine exists. The vaccine against human papillomavirus (HPV), the virus that causes almost all cervical cancer, is the best-known example. Dr. Agarwal cited a protection rate of 98 per cent when it is given to girls. Hepatitis B vaccination also lowers the risk of liver cancer by preventing chronic hepatitis B infection.

Prevention: screening, warning signs and lifestyle

Asked what can be done to prevent cancer deaths, Dr. Agarwal returned to the same two levers, screening and the warning signs, and added a third: a healthy lifestyle. Regular exercise, no tobacco, a minimum of alcohol and a balanced diet are, in his words, very important. A person who does all of this will either not develop cancer or will have it diagnosed early.

Smoking is the dominant single risk. He describes it as the most common risk factor for cancer across the world, across both genders and every race and ethnicity, and the risk factors article sets out his case against it in full, alongside the role of diet and nutrition.

How cancer treatment has changed

Treatment today is tailored to the individual. Dr. Agarwal summarised the current approach as the right drug, at the right dose, in the right patient, to get the best outcome. It is not one size fits all.

Three families of medical treatment now sit alongside surgery and radiation. Chemotherapy is any drug that enters the body and kills cancer cells. Targeted therapy acts only on cells carrying a specific target. Immunotherapy prompts the patient's own immune system to kill the cancer, and he describes it as the game changer in cancer management. Radiation has also become more precise: image-guided radiotherapy, which uses imaging during treatment to direct the beam, treats any part of the body in a specific manner with minimal toxicity. The detail, including the order in which these treatments are combined in breast cancer, is in Can Chemotherapy and Hormone Therapy Be Given Together?. Specialists and other masterclasses in the field are gathered on the oncology specialty hub.

Is cancer curable?

Cancer is a curable disease when it is picked up at the right stage and treated correctly at the right time. Dr. Agarwal closed the circle on his opening definition: cancer may be a scary word, but it is just a word and not a death sentence if treated properly. Survival, he showed, has been increasing year on year with newer technologies.

He also runs a public education programme, Stop Cancer in India, which teaches people and doctors about the risks of cancer and how to overcome them.

The questions doctors raised at the end of the session, on tumour markers in ovarian cancer, brain tumour relapse, a male patient with breast discharge and nutrition in advanced cancer, are answered on the Live Discussion page. Dr. Agarwal's later masterclass for the same network is summarised in Cancer Myths, Facts and Advances: A Complete Guide.