Australian Study Finds General Practitioners Tend to Adhere to Guidelines When Treating Melanoma

The high rate of melanoma management by general practitioners (GPs), as opposed to specialists, does not appear to impact survival rates or the likelihood that guidelines are followed, according to a new report based on treatment data from Australia and New Zealand.

As of 2014, about half of Australian patients (49%) with melanomas had their cases handled by GPs, rather than by dermatologists or surgeons, according to corresponding author Cliff Rosendahl, MBBS, PhD, of the University of Queensland. That rate was up from 43% of patients in 2003.

“The increase in management by GPs has raised questions about the quality of management in that setting, for which limited data are available,” Rosendahl and colleagues wrote in the Australasian Journal of Dermatology.

The investigators turned to the Skin Cancer Audit Research Database, a trove of real-world skin-cancer data first established in 2006. From that database, they identified 27 GPs (24 in Australia; 3 in New Zealand) who consented to participate in the study and who affirmed that their data from the study year 2013 was complete. From those physicians, the investigators were able to identify and analyze 589 patients with 637 melanomas.

Most of the patients in the dataset were men, with a mean age of 62.7 years at diagnosis. An analysis of the cases showed that most cases (65%) were in situ melanomas, rather than thin-invasive, although patients under the age of 40 were more likely than older patients to have invasive melanomas.

The majority of melanomas were diagnosed based on an elliptical excision biopsy (55.9%), with shave biopsies to the mid-dermis reported as the second most common diagnostic technique (32.2%).

In three-quarters of cases, wide re-excision was performed by the GP, but thick melanomas tended to be referred to surgeons, Rosendahl and colleagues said. Those melanomas re-excised by GPs had an average Breslow thickness of 0.69 mm, compared with 1.99 mm in patients who were referred to specialists. Fourteen of the 205 patients with invasive melanomas progressed to metastatic disease, the authors said, with half of those cases associated with nodular melanoma. Nine patients had melanoma-specific death; the 5-year survival rate was 95.2%.

Rosendahl and colleagues said the findings from their study fall broadly within guidelines currently in place in the region and in 2013.

Those guidelines “recommend elliptical excision biopsy for suspected melanoma, with 2-mm peripheral margins undermined in the subcutis, and in the current study, this was adhered to for 55.9% of lesions,” the authors said.

Shave biopsy is considered an “expedient and reasonable alternative,” they added. However, they also noted that the rate of unintended positive margin involvement was 8 times higher for shave biopsy versus excisional biopsy in the study, which they said ought to serve as a warning about the “potential hazards to consider when deviating from guidelines.”

In discussing the melanoma cases that led to metastatic disease and death, the authors noted that half of the 14 melanomas that progressed to metastatic disease were located in high-risk areas, such as the scalp, neck, back, and arm. They added that the average Breslow thickness of the melanomas was 3.9 mm, a figure consistent with a higher risk of adverse outcomes, according to earlier research.

However, they added that 2 of these melanomas had a Breslow thickness of just 0.5 mm and one of those patients died as a result of melanoma. Rosendahl and colleagues said those outlier cases serve as a reminder that all melanoma needs to be treated as life-threatening, at least until the science gets to a point where markers can reliably predict which melanomas are most likely to progress to adverse outcomes.

Reference:

Hay J, Keir J, Jimenez Balcells C, et al. Characteristics, treatment and outcomes of 589 melanoma patients documented by 27 general practitioners on the Skin Cancer Audit Research Database. Australas J Dermatol. Published online April 19, 2022. doi:10.1111/ajd.13843