New Zealand has one of the highest rates of skin cancer in the world. Most skin cancers are basal cell or squamous cell carcinomas, and most are cured by a small operation under local anaesthetic. This guide explains what these cancers are, why surgery is the usual treatment, what the pathology report means, how the wound is closed, and what to expect on the day and afterwards. Melanoma is covered in a separate guide.

What are basal cell and squamous cell carcinoma?

Skin cancer starts in the cells of the outer layer of the skin. The two most common types are (BCC) and (SCC). Together they are called keratinocyte cancers, or non-melanoma skin cancers.
BCC is the most common cancer of all1. It grows slowly and very rarely spreads to other parts of the body — about one in a thousand or fewer2. Left alone, though, it keeps growing into the skin and the tissues underneath. That is why it is treated1.
SCC grows faster and can spread, but this is uncommon. In large studies about 4 in 100 SCCs spread to the lymph glands, and more than 9 in 10 are cured34. The risk is higher for large or thick tumours, tumours on the ear or lip, and in people whose immune system is suppressed5.
Both cancers are caused mainly by sun exposure over many years. Fair skin, age and a weakened immune system add to the risk4. People who have had an organ transplant are at much higher risk, especially of SCC, and need lifelong skin checks6.

Skin cancer in New Zealand

New Zealand and Australia have the highest rates of keratinocyte cancer in the world78. Around 90,000 are diagnosed in New Zealand each year9. In one New Zealand region, new cases of BCC rose by about 4 per cent a year between 1999 and 2007, mostly in people over 508. Squamous cell carcinoma is more common here than almost anywhere else10. Fair skin, strong sunlight and an outdoor way of life are the reasons.

Why surgery is the usual treatment

For most BCCs and SCCs, cutting the cancer out is the first-choice treatment111. It removes the whole tumour in one visit. The tissue is then sent to the laboratory to confirm the diagnosis and to check that the cancer has been removed completely. Other treatments — creams, freezing, scraping or radiotherapy — have a place for some low-risk tumours, or when surgery is not possible1. For most tumours, surgery gives the lowest chance of the cancer coming back, and the clearest answer.

Margins and the pathology report

A skin cancer often extends a little beyond what can be seen. To remove it completely, the surgeon takes a rim of normal-looking skin around it. This rim is called the . For a small, well-defined BCC, a margin of about 4 mm removes the whole tumour in more than 95 out of 100 cases12. For SCC the margin is 4 mm for low-risk tumours and 6 mm or more for higher-risk ones1314. Larger, ill-defined or recurrent tumours need wider margins15.
The tissue is examined under the microscope. The report states the type of cancer, how deep it went, and whether the edges are clear of tumour. A margin is usually called clear when at least 1 mm of normal tissue surrounds the cancer1514.
Sometimes the report shows cancer at or very close to the edge. This is called an incomplete excision. It happens in roughly 1 in 10 excisions16. It is more common on the nose, eyelids and ears, where the surgeon keeps the margin small to protect important structures17. Not all of these grow back, but about 1 in 4 do if nothing more is done1819. Your surgeon will discuss the options: a further excision, Mohs surgery, radiotherapy, or careful watching for a low-risk BCC15. After a complete excision, a BCC comes back in fewer than 2 in 100 cases20.

Mohs surgery

Mohs micrographic surgery removes the tumour in thin layers. Each layer is checked under the microscope during the operation, until the edges are clear. It gives the lowest recurrence rates for high-risk tumours on the face, and it spares as much normal skin as possible. In a ten-year trial of facial BCCs, recurrent tumours came back in 4 in 100 after Mohs surgery and in 13 in 100 after standard excision; for first-time tumours the difference was smaller and not proven2122. Mohs surgery is used for recurrent, ill-defined or aggressive tumours in important sites such as the nose and eyelids15. In New Zealand it is offered by a small number of trained dermatologists, and it is not needed for most skin cancers23.

Closing the wound

How the wound is closed depends on its size, where it is, and how loose the surrounding skin is.
  • Direct closure. For most small wounds the edges are brought together with stitches, leaving a straight scar24.
  • Local flap. A moves nearby skin, still attached to its blood supply, into the wound. It gives a close match of colour and thickness and is often used on the nose, cheek and forehead24.
  • Skin graft. A is a piece of skin taken from elsewhere and stitched into the wound25. The skin usually comes from in front of or behind the ear, above the collarbone, the inner upper arm or the groin, where the scar is easy to hide. A firm padded dressing holds the graft still and is left untouched for about a week, then removed in clinic. Grafts take well in most cases but can look paler or flatter than the surrounding skin26.
  • Healing by secondary intention. Some wounds are left open to heal on their own. On hollow parts of the face, such as the inner corner of the eye, this can give an excellent result2728. It takes several weeks and needs regular dressings.

The day of surgery

Most skin cancer operations are done under local anaesthetic as a day case. You can eat normally beforehand and go home afterwards. The anaesthetic is injected around the lesion. The injection stings for a few seconds and then the area goes numb. It usually contains adrenaline to reduce bleeding. The operation usually takes less than an hour; a simple excision takes about half an hour, and a flap or graft takes longer. If you take blood-thinning medicines, keep taking them unless your surgeon tells you otherwise; stopping them carries more risk than a little extra bruising29.

Wound care, scars and results

Keep the dressing dry for the first two days unless you are told otherwise. After that, a thin layer of plain petroleum jelly keeps the wound moist. Antibiotic ointments are no better and can cause skin allergy30. Wound infection is uncommon — around 2 to 6 in 100 in published studies, including a New Zealand trial — and is treated with antibiotics if it occurs3130. Stitches on the face come out about five to seven days after surgery; on the trunk, arms and legs they come out at ten to fourteen days32. Some stitches dissolve on their own and do not need removing; a skin graft is usually stitched in this way, so only its dressing is taken off.
Every operation leaves a scar. It is red and firm at first, then softens and fades over about a year33. Massage with a plain moisturiser from a few weeks after surgery, and protecting the scar from the sun for a year, help it settle. Silicone gel or sheets can help if a scar becomes raised34. A flap or graft may look lumpy or mismatched for several months. Most settle, and a small revision can be done later if needed.

Follow-up and skin checks

Your surgeon will see you to check the wound and go through the pathology report. What follows depends on the report. A single low-risk BCC that has been fully removed does not usually need hospital follow-up15. Higher-risk SCCs are checked regularly for two to three years14.
Having one skin cancer means you are likely to have another. About one in three people develop a further skin cancer within three years of their first, and about four in ten within five years35. Check your own skin every few months and see your GP about any new or changing spot. People who have had several skin cancers benefit from a yearly full-skin check15.

Sun protection

Protecting your skin lowers the chance of more skin cancers. In an Australian trial, using sunscreen every day cut the number of new SCCs by about 40 per cent, and the benefit lasted for years afterwards3637. The SunSmart advice is to slip on covering clothing, slop on broad-spectrum SPF 30 or higher sunscreen, slap on a wide-brimmed hat, and wrap on sunglasses — from September to April, and whenever the UV index is 3 or more38. For people who have had several skin cancers, a vitamin B3 tablet (nicotinamide 500 mg twice a day) reduced new skin cancers by about a quarter in a trial39. Ask your doctor whether it is right for you.

When to seek help

Contact your surgeon or GP if:
  • the wound bleeds and does not stop after ten minutes of firm pressure;
  • the wound becomes increasingly red, swollen or painful, discharges, or you develop a fever;
  • a graft or flap turns dark or breaks down;
  • a lump, sore or scaly patch appears in or near the scar;
  • you notice any new or changing spot elsewhere on your skin.
Your GP can refer you to a plastic surgeon or a dermatologist.