Patients with cutaneous invasive head and neck melanomas (HNM) do worse than those with non-HNM but the reasons for the disparity are unclear.

A retrospective Queensland study, using data from the Cancer Alliance Queensland’s Oncology Analysis System (OASYS) over a 10-year period from 2009 to 2018, compared incidence and survival of 5,813 patients with HNM and 30,643 with non-HNM.

Ear and external auricular canal, eyelid including canthus, lip, scalp and neck and other and unspecified parts of the face were classified as HNM.

The study found HNM were more common in older patients (65.5 v 60.7 years) and seen in a higher proportion of males (68.1% v 57.0%).

There was also a higher proportion of ulcerated lesions (16.7%) and a Breslow thickness greater than 1mm (35.6%) in HNM than in non- HNM.

The study, published in the Australasian Journal of Dermatology [link here], found 5-year and 10-year survival probabilities for patients with HNM were 90.7% and 89.1% respectively, compared to 94.7% and 93% in patients with non-HNM.

Patients with HNM died from melanoma at 1.22 times (HR 1.22; 95% CI: 1.09– 1.37) the rate of patients with non-HNM after adjusting for variables of sex, age, socioeconomic status, remoteness, Breslow group, presence of multiple invasion melanoma and ulceration.

“Moreover, the multivariable analysis determine that males were 1.45 times (HR 1.45; 95% CI: 1.30– 1.61) more likely to die from melanoma than females, and the risk is increased with older age per 10-year period (HR 1.21; 95% CI: 1.17– 1.25),” it said.

Scalp melanoma even worse

Within HNM, the survival curve was even worse for scalp melanoma compared with other HNM sites.

It found 10-year survival probabilities for scalp melanoma was 75.5% compared to the neck at 90.9%, other and unspecified parts of the face at 91.5%, and ear and external auricular canal at 94.3%.

Patients died from scalp melanoma at 1.57 times (HR: 1.57; 95% CI: 1.26–1.95) the rate of HNM non-scalp patients after adjusting for the same variables of sex, age, Breslow thickness, multiple invasive melanomas and ulceration.

“Given that scalp melanoma represented 2.7% of all melanoma patients but represented 8.7% (150/1721) of all deaths from melanoma, it is clearly a particular subset of melanomas that requires specific consideration,” the investigators said.

They said there was no clear explanation as to why patients with HNM have poorer survival than those with non-HNM.

“Some authors have submitted that HNM do not receive sufficient margin resection as patients and clinicians may have concerns regarding cosmetic appearance or functionality.”

“Other papers have suggested that the complex vascular supply and lymphatic drainage of the head and neck may allow the entry and distribution of melanocytes into the systemic circulation,” the study said.

As for the added risk with scalp melanomas, it was suggested that hair coverage could lead to late diagnosis and consequently a poorer prognosis.

The investigators said current screening and clinical guidelines should be reviewed to ensure that thorough physical examinations of the head and neck are conducted.

“Second, members of the public should be educated about the potential implications of head and neck melanoma so that they are encouraged to adopt preventative and screening measures.”

“Finally, given the lack of explanation as to why head and neck melanoma and scalp melanoma are associated with poorer survival outcomes, further research in this area should be done so a more definitive rationale can be established. This may assist with the development of better management protocols for patients with head and neck melanoma,” they concluded.