Anal cancer

This is an uncommon tumour, accounting for roughly one or two per cent of all malignant tumours of the bowel. It develops at the very end of the digestive tract, in a short canal three to four centimetres long that lies between the rectum and the skin around the anus. Two things are worth knowing from the start: it is almost always caused by a virus that a vaccine protects against, and it responds well to treatment when found early. The difficulty is that its first signs look exactly like piles, so people often spend months treating the wrong thing.

Where the tumour actually grows

The anal canal is not lined by bowel mucosa but by tissue closer to skin. That is why the tumour arising here differs from rectal cancer: in most cases it is a squamous cell carcinoma, the same type that appears on the skin and on the cervix. It may grow inside the canal or right at the edge, on the visible skin, and this affects both treatment and outlook.

Other varieties turn up occasionally, such as adenocarcinoma and anal melanoma. Melanoma here is very rare but behaves aggressively, and it often looks like an ordinary dark lump, a supposed pile. For that reason any new dark spot beside the anus deserves a look from a doctor rather than watchful waiting.

What people notice first

The signs are subtle and build up gradually:

• bright red blood on the paper or on the surface of the stool;
• pain or a feeling of pressure, sometimes worse when sitting;
• itching, dampness, a discharge of mucus;
• a firm lump or a sore beside the anal margin that will not heal;
• a sense of incomplete emptying, false urges to go;
• stools that have become looser and more frequent;
• trouble holding in wind or stool;
• a lump in the groin, which may be an enlarged lymph node.

The tumour can cause no sensation at all for a long time and be found during an examination carried out for another reason.

Why it gets mistaken for piles

Blood, itching and a lump beside the anus form a picture almost everyone puts down to piles, and the great majority of the time they are right. The danger lies not in that conclusion but in the habit of testing it alone for years: suppositories are bought, the symptom quietens for a while, the appointment is postponed. The distinction is simple: piles and fissures retreat under treatment, a tumour does not. Hence the rule of thumb — if bleeding, pain or a lump lasts longer than three weeks, or returns after a seemingly successful course of treatment, the diagnosis needs an examination rather than an assumption.

When waiting is the wrong choice

Book an appointment within days, without waiting for it to settle on its own, if any of the following appears:

• bleeding from the anus, especially for the first time after the age of forty-five;
• a sore that does not heal or a lump that is getting bigger;
• pain in the area lasting more than two or three weeks;
• new difficulty holding in wind or stool;
• a lump you can feel in the groin;
• unexplained weight loss, tiredness, a lasting change in bowel habit.

Straight away, to an emergency department or by ambulance: heavy bleeding with weakness and dizziness, severe pain with a high temperature and swelling around the anus, an inability to pass urine or to open the bowels.

Where it comes from: human papillomavirus

In about nine cases out of ten the tumour contains human papillomavirus, the same virus behind cervical cancer. It passes on through any close contact of skin and mucous membranes in the genital area, not only through intercourse, and it is so widespread that most adults catch it at some point. In nearly all of them the immune system clears it within a year or two and nothing further happens. The tumour develops in the few in whom the infection stays for decades.

What makes that outcome more likely:

• smoking, one of the strongest factors, acting independently of the virus;
• weakened immunity: HIV, medication after an organ transplant, long courses of treatment that damp down the immune system;
• a previous cancer of the cervix, vagina or vulva, all linked to the same virus;
• anal intercourse and a high number of partners;
• age: the disease becomes more common after sixty.

What can be done in advance

This is one of the rare cancers where prevention genuinely works.

Vaccination against human papillomavirus. It protects against the virus types responsible for most of these tumours, and works better the earlier it is given, before sexual activity begins. Across Europe it is offered to adolescents of both sexes, and some programmes extend it to adults at higher risk. Ask your doctor what is available where you live.

Stopping smoking. It lowers the risk and, if the disease has already been found, noticeably improves how treatment is tolerated.

Condoms. They protect only partly, because the virus also lives on skin a condom does not cover, but they do cut the chance of infection.

Surveillance for those at high risk. People living with HIV and transplant recipients are offered, in some centres, regular examination of the area and an anal smear, so that changes are caught before they become a tumour.

How the diagnosis is confirmed

It starts with the simple things: the doctor examines the skin around the anus, performs a digital examination, then looks inside the canal through a short lighted tube. Only a biopsy makes the diagnosis — a small piece of tissue sent to the laboratory. Without it, no scan can answer the question.

Once the tumour is confirmed, its size and spread are mapped out: magnetic resonance imaging of the pelvis, computed tomography of the chest and abdomen, ultrasound of the groins with a needle sample from any suspicious node and, at times, a positron emission scan. An HIV test is usually offered too, and not as a formality: the state of the immune system shapes the treatment plan.

How it is treated

The mainstay is not surgery but radiotherapy combined with chemotherapy: cytotoxic drugs are given alongside the radiation to strengthen its effect, over a course of several weeks. This preserves the anus and its sphincter muscle, which is why most people do not need a stoma.

One point matters here: the tumour shrinks slowly, and a complete response sometimes arrives only several months after the course ends. Doctors therefore do not rush to conclusions and assess the result at set intervals.

Surgery is used in two situations: when the tumour is very small and sits at the skin edge, where it can simply be cut out; and as a fallback if the tumour persists or comes back after chemoradiotherapy. The operation is then larger and a permanent stoma may be needed.

During treatment there is almost always soreness of the skin of the perineum, loose stools, fatigue and a drop in blood counts — all expected, and all supported. Longer-term effects are discussed in advance: the possible impact on fertility, vaginal dryness and narrowing, changes in erection, urgency to open the bowels. If having children is part of the plan, storing sperm or eggs is arranged before treatment starts, not afterwards. Follow-up then continues for several years, with examinations and scans, so that any return of the disease is caught while it can still be dealt with.

Online consultation: how it helps

Examining this area calls for a face-to-face visit and nothing replaces it remotely. Talking to a doctor online answers a different set of questions: whether your symptoms fit piles or a fissure, and how soon an examination is needed; what the biopsy report and the stage mean once a diagnosis has been made; which questions to put to the specialist. Another frequent topic is the papillomavirus vaccine — who it makes sense for and at what age. And if walking in with a complaint like this feels awkward, starting the conversation from home is easier, and far better than never starting it.

This material is for information only and does not replace medical advice.