More than half of Australians will develop skin cancer in their lifetime, with melanoma currently the third most common cancer in Australia.

GPs are crucial as the first line in diagnosis and management, says Associate Professor Robyn Saw of the Melanoma Institute of Australia.

She describes the highest risk patients as those with fair skin who have grown up in Australia with significant sun exposure. “It’s the young exposure to blistering sunburn that’s important,” she says, although she is also concerned about occupational sun exposure.

Associate Professor Saw lists other risk factors that are important. “Patients who’ve had other skin cancers, including melanoma previously, you need to take notice of their skin. And also patients with lots and lots of naevi, the so-called dysplastic naevus syndrome, which is now called Multiple Naevus Syndrome,” she says. “People with more than 100naevi are most likely, almost 100% likely to get a melanoma in their lifetime.”

Identifying high risk patients for melanoma:

• Fair skin
• Grew up in Australia
• History of severe sunburn at a young age
• Significant occupational sun exposure
• Previous skin cancer (both melanoma and non-melanoma)
• Multiple Naevus Syndrome
• Family history

Diagnosing melanomas

Associate Professor Saw says the key to an effective skin check is a careful history from the patient. With most melanomas (60%) arising from previously normal skin, and the remainder arising in a pre-existing naevus, the patient’s report of a new or changing lesion is often crucial. She is confident most GPs will use the ABCDE rule to assess lesions macroscopically, but does caution that amelanotic melanomas are increasing in incidence, now accounting for 20% of cases.

Dermoscopy is critical in deciding whether to biopsy a lesion. Although polarising dermatoscopes allow a faster skin examination without the need for oil or gel, contact dermatoscopes are important for examining the nail bed. Associate Professor Saw says some dermatoscopes can toggle between polarising and contact modes.

For a suspicious flat lesion without clear indication for biopsy, Associate Professor Saw says it is acceptable to monitor over 3 months using digital dermoscopic pictures. (“However, if something is raised or nodular, you cannot do sequential monitoring. You need to biopsy,” she clarifies.)

For flat lesions that remain unchanged over 3 months, more than 99% are benign, she says. “There will be a few melanomas that escape this monitoring, but if you’re uncertain at 3 months, you can do another 3 month monitoring. You pick up thinner melanomas with this sequential monitoring.”

“The other thing that’s taking off is total body photography,” Associate Professor Saw says. She recommends this for patients with more than 100 moles. “This is an area of bounding research with the use of AI and 360 degree photos,” she comments, although she doesn’t think computers will take the place of clinicians any time soon.

The ideal biopsy is a complete excision with 2 mm margins, to give the pathologist as much tissue as possible. Associate Professor Saw says it’s not always easy to remove a lesion fully for biopsy, for example if it is particularly large or in a cosmetically significant location. This may necessitate a partial biopsy, such as a punch, shave/saucerisation or incision.

In these situations, she has a few tips to ensure the biopsy is diagnostically adequate. She says the biopsy must be deep enough to include the base of the lesion, and if choosing a punch biopsy, pick the largest punch you can. “If there is pigmentation beyond the actual lesion that may be a satellite, you need to include that,” she says.

For an incision biopsy in a particularly large lesion, she recommends taking the sample from the thickest and/or most abnormal looking region. “You don’t need to include normal skin from the edge like we used to be taught.”

The laboratory should provide a synoptic report that covers all the lesion factors that are important in deciding on treatment. “The most important is the Breslow thickness from the stratum granulosum down to the last melanoma cell,” she says. This impacts the size of the wide local excision, and decisions about treatment for involved lymph nodes.

Treatment and follow up

The mainstay of treatment for primary melanoma remains a wide local excision, with the margins depending on the thickness. This is nevertheless a still-evolving field. Recent guidelines have increased the margins for lentigo maligna compared to other melanoma-in-situ because of the associated field of sun damage.

An Australian study currently in progress is attempting to decrease the margins needed for intermediate and thick melanomas. If successful, this may decrease the number of patients needing grafts, and improve cosmetic outcomes.

Associate Professor Saw says “We know that the risk of metastasis to lymph nodes depends on the thickness of the lesion primarily, but also ulceration status and mitotic rate.” These factors and an examination of the draining nodal field inform a decision to offer sentinel node biopsy. This procedure, performed under general anaesthetic, is not without risks, including the development of lymphoedema.

A positive sentinel node biopsy used to mean a completion dissection (the removal of the rest of the local nodes), however this has been shown to offer no survival benefit. “In this new age of exciting melanoma drug treatment, we actually recommend adjuvant drug therapy to reduce the risk of melanoma coming back in the future.”

When to refer a patient with a primary melanoma to a melanoma surgeon:

• Melanoma-in-situ/thin melanoma in a difficult area or if the margins are difficult to identify – for help with the wide excision
• 0.8 – 1 mm Breslow thickness with adverse features (Clark level IV or V, ulcerated, high mitotic rate) – to discuss sentinel node biopsy
• > 1 mm Breslow thickness – to discuss sentinel node biopsy

Follow up for Stage I and II melanomas focuses on education and surveillance. Photoprotection is vital in preventing future skin cancers, and the patient should also be trained to self-examine their skin. Clinic visits are more frequent to begin with (3-6 monthly), then yearly, often alternating between the GP and the dermatologist or melanoma surgeon. Imaging is rarely required (except sometimes ultrasound of lymph nodes). She suggests checking Vitamin D levels and recommending oral supplementation if appropriate.

If a patient presents with suspected nodal disease, the role of the GP is to confirm the diagnosis with fine needle biopsy (+/- ultrasound). “Then leave the rest for us,” says Associate Professor Saw. The patient will need staging PET and brain scans, and usually a therapeutic lymph node dissection before adjuvant drug therapy, but this will be handled by the melanoma specialist.

Follow up of these Stage III patients will still usually involve the GP. The plan is very similar to lower stage patients, with the addition of imaging (PET and brain scans) and additional blood markers (LDH and liver function tests).

Stage IV disease involves systemic metastases. Previous chemotherapy worked poorly with very minimal long term survival. Associate Professor Saw notes the two newer types of medication on the market – targeted therapy and immunotherapy.

As the name suggests, targeted therapy targets a particular type of abnormality in the melanoma cell. These drugs work quickly, but the effects don’t last. “They buy patients time,” says Associate Professor Saw, “but the majority will have recurrence by 9 months.”

Immunotherapy stimulates the patient’s immune system to fight the melanoma, and may increase survival by up to 40%.

Associate Professor Saw is speaking at Healthed’s free webcast on 25 July. Register here for more practical melanoma management tips. She also recommends free accredited education modules and resources available via the Melanoma Institute of Australia (https://melanomaeducation.org.au/) to any GPs looking to upskill further.