Cancer Warning Signs: When to Suspect Cancer by Type

The warning signs of cancer follow recognisable patterns. The CAUTION mnemonic captures the seven classic signals: a change in bowel or bladder habits, a sore that does not heal, unusual bleeding or discharge, a lump or thickening, indigestion or difficulty swallowing, an obvious change in a wart or mole, and a nagging cough or hoarseness. Loss of appetite and significant weight loss are common to most cancers.

Dr. Nithin S.G, Consultant, Medical Oncology, Fortis Flt. Lt. Rajan Dhall Hospital, Vasant Kunj, New Delhi, India, framed the warning signs as a tool for general practitioners and for people who are not doctors at all. Most cancers are first seen by someone who is not an oncologist. Whether the disease is caught at a curable stage depends on that first doctor asking the right question. This article sets out his symptom checklist by cancer type, and the examination that should follow. For the full pathway from detection to recovery, see the complete guide to cancer care.

The CAUTION mnemonic: seven warning signs of cancer

A person should be cautious about cancer, and the word itself is the memory aid. Each letter stands for one warning sign:

• C: Change in bowel or bladder habits.
• A: A sore or ulcer that does not heal.
• U: Unusual bleeding or discharge from any site.
• T: Thickening or a lump in the breast or any other part of the body.
• I: Indigestion or difficulty in swallowing.
• O: Obvious change in a wart or mole.
• N: Nagging cough or hoarseness.

The mnemonic is deliberately broad. It will not identify which cancer a patient has, but it is a simple way to remember the major symptoms of most cancers, for doctors and non-doctors alike.

Breast cancer signs: not always a lump

A breast lump must always be evaluated, but not every breast cancer presents as one. Dr. Nithin stressed that skin and nipple changes can be the only sign. The warning signs are:

• A lump in the breast.
• Redness of the skin over the breast.
• Dimpling of the skin.
• Nipple retraction (the nipple pulling inwards).
• Discharge or fluid from the nipple.
• Breast pain.
• An ulcer or nodule on the skin of the breast.

Even when the examining doctor finds no lump, any of these changes should raise the suspicion of breast cancer and prompt further tests. Breast cancer is the most common cancer in women, so the threshold for investigation should be low.

Oral and throat cancer symptoms

Oral cancer is closely linked to tobacco, and Dr. Nithin advised examining the mouth of every patient who smokes or chews tobacco or paan. The red flags are:

• An ulcer in the mouth lasting more than three weeks without healing.
• An ulcer that bleeds on touching or while brushing.
• A lump in the mouth or throat, including an enlarged tonsil.
• An ulcer or lump on the tongue.
• Difficulty in swallowing, or a sore throat that has persisted for two to three weeks.
• In older people with dentures: loosening teeth, dentures that no longer fit, or new pain or difficulty when wearing them.

Any of these warrants a thorough examination of the mouth, ideally by an ENT surgeon.

Colon and rectal cancer symptoms

Cancers of the colon and rectum typically produce:

• Blood in the stool, or black stool.
• Abdominal pain.
• Excessive weight loss.
• Severe fatigue.
• A lump in the abdomen.

The fatigue has a physical cause. Most patients with colon or rectal cancer lose blood in the stool, often unnoticed, and the resulting anaemia makes them tired. Passing blood or black stool is the classic symptom.

Oesophageal and stomach cancer symptoms

The defining symptom of cancer of the oesophagus (the food pipe) is difficulty swallowing. The pattern is characteristic: patients can still swallow water, but solid food sticks or is painful to swallow.

Stomach cancer presents differently:

• Repeated gastritis that does not respond to standard medication.
• Vomiting.
• Severe weight loss and loss of appetite.
• Early satiety: feeling full after eating very little.

Repeated gastritis that does not settle on normal medication, together with vomiting, weight loss and early satiety, should prompt investigation for stomach cancer.

Liver, gallbladder and pancreatic cancer symptoms

These cancers share a set of upper abdominal symptoms:

• Pain in the right upper abdomen (the right hypochondrium), typical of liver and gallbladder cancer.
• Jaundice.
• Pain in the centre of the abdomen radiating to the back, which is very characteristic of pancreatic cancer.
• Abdominal distension.

Dr. Nithin's specific advice concerned older patients with jaundice. If an elderly patient presents with jaundice and the initial evaluation finds no cause, always test for gallbladder or pancreatic cancer.

Bladder, kidney and prostate cancer symptoms

• Bladder and kidney cancer: blood in the urine, with or without lower back pain.
• Prostate cancer: difficulty passing urine, a feeling that the bladder has not emptied completely, urinary hesitancy and urgency.

The prostate symptoms overlap heavily with benign enlargement of the prostate, which is why the work-up matters. The diagnosis article explains what a raised PSA can and cannot tell a doctor.

Cervical and uterine cancer symptoms

• Cervical cancer: vaginal bleeding, most often after sexual intercourse; vaginal discharge; lower abdominal pain.
• Uterine cancer: postmenopausal bleeding, meaning renewed or repeated bleeding in a woman who has already reached menopause.

Abdominal pain, constipation and urinary discomfort can accompany either. A fuller account of these cancers is in the overview of gynaecological cancers.

Lung cancer symptoms: four classic signs

Dr. Nithin listed four symptoms that should make a doctor think of lung cancer, particularly in a current or former smoker:

1. A dry cough lasting more than three to four weeks, with no sputum and no evidence of infection.
2. Breathlessness.
3. Blood in the sputum. Whenever a patient reports coughing blood, the possibility of cancer should be considered.
4. A lump in the lower neck. Lung cancer often spreads to the lymph nodes at the base of the neck, and an enlarged node there can be the presenting sign.

An enlarged node in the neck can therefore be a lung cancer symptom, not only a head and neck one.

Skin cancer and melanoma warning signs

Skin cancer is especially common in European countries. The warning signs concern moles:

• An existing mole that is growing rapidly.
• Borders becoming asymmetrical or irregular.
• A rapid change in colour.
• New moles appearing.
• A mole that bleeds, itches, ulcerates or becomes a nodule.

Melanoma is the most dangerous skin cancer. It is usually dark brown or black, though some are pink or skin-coloured, and it appears most often on the back in men and on the legs in women. It may start as a small mole and then grow quickly. In all of these cases, Dr. Nithin's instruction was unambiguous: biopsy the lesion.

Weight loss and loss of appetite: signs common to most cancers

Organ-specific symptoms vary, but most cancers consistently produce two general ones:

• Decreased appetite. Patients eat less and their diet shrinks.
• Severe weight loss with fatigue.

Significant unintentional weight loss is usually defined as more than 5% of body weight over six to twelve months; Dr. Nithin also treats a loss of more than 10 kg over six months as a clear red flag. An older patient who says they feel very weak and have lost weight on that scale should be tested for cancer, even if there is no lump, no cough and no jaundice.

Blood cancer symptoms

Blood cancers present through the blood and the bone marrow rather than through a mass. The symptoms are:

• Severe weakness.
• Bleeding from the gums, bruising on the skin, a pinpoint red rash, or blood in the urine.
• Enlarged lymph nodes.
• Bone pain, particularly at night.

These patients need a complete blood count first; the diagnosis article covers the confirmatory tests.

What to examine when cancer is suspected

Symptoms open the question; examination narrows it. Dr. Nithin set out what every patient with a possible cancer symptom should have examined, whatever the presenting complaint:

• The site of the symptom: the breast, the abdomen, or wherever the patient has noticed a change.
• The neck, for enlarged lymph nodes. Always.
• The armpits, in any patient with breast pain or a breast lump. The primary cancer may not be obvious, and a lymph node in the armpit can be the only site where it is found.
• The mouth, for ulcers.
• Signs of anaemia.

The point of the full examination is that the cancer may not be well seen at its origin: it may already have spread to a lymph node, and that node may be the only place it can be found.

From suspicion to diagnosis

A warning sign is a reason to investigate, not a diagnosis. The next steps are blood tests, the right imaging and, above all, a properly taken biopsy. Those steps are covered in how cancer is diagnosed. How the diagnosis then shapes treatment, from conventional therapy to targeted therapy and immunotherapy, is covered in the remaining articles of the series.

Questions from the doctors who attended, including on breast imaging and testicular swellings, are on the Live Discussion page.