Scientists have long debated the significance of tumor location in determining cancer prognosis.
Understanding how melanoma's location factors into a patient's survival is important for public health messages on skin awareness and sun protection, because using sunscreen, avoiding direct sunlight, and wearing sun-protective clothing such as hats to cover the scalp play a large role in preventing the cancer.
"Moreover, because the role of screening in melanoma is considered important for early detection, it is useful to clarify those characteristics with prognostic significance," study author Anne M. Lachiewicz, MPH, of the University of North Carolina School of Medicine, says in a news release.
For the study, Lachiewicz and colleagues looked at cancer data for 51,704 non-Hispanic white people who were first diagnosed with melanoma between 1992 and 2003. Most had melanomas involving the arms, legs, or middle of the body (trunk area). Only 6% had melanoma involving the scalp or neck. The team found a notable survival difference between scalp/neck melanomas and melanomas on other parts of the body.
Among their findings:
The 5-year survival rate for those with scalp/neck melanomas was 83.1% compared with 92.1% for those with melanomas at other sites.
The 10-year survival rate for those with scalp/neck melanomas was 76.2% compared with 88.7% for those with melanomas at other sites.
Persons with scalp/neck melanomas died at nearly two times the rate of those with melanomas on the arms and legs, even after taking into consideration other negative factors such as age and tumor thickness.
The reason for the worse survival among the patients with scalp/neck melanomas is unclear, but the study authors point out that a complex blood supply and lymphatic drainage system in the scalp and neck area may make it easier for melanoma cells to penetrate and circulate. Patients with melanomas of the head and neck are also more likely to have the cancer spread to their brain than those with melanomas affecting the extremities and trunk.