Those of you coming back from spring break with glorious tans may have some cause for concern, according to a Harvard Medical School research team.

Blistering sunburns during adolescence seriously increase the early risk of acquiring a malignant and at times fatal skin cancer, concluded a recent study authored by Harvard doctors and conducted at Massachusetts General Hospital.

Melanosis, which is fatal in one out of every four cases, can result from short, intense exposure to the sun. This type of skin cancer, unlike the other two, generally non-fatal forms, is not related to total lifetime exposure.

Adolescents spending at least one month per year vacationing in sunny areas will have twice the risk of developing a melanoma, regardless of whether they tan well or not at all, the study found.

"We're not advocating people giving up what they want to do, but [we're saying they should] be more careful," said researcher Dr. Arthur J. Sober, associate professor of dermatology.

With victims of the disease averaging only 40 years in age, melanosis has the earliest occurence rate among skin cancers, sometimes striking victims during their teenage years.

Sober said tanners should use sunblock lotion, avoid the intense midday sun, or wear protective clothing while in the sun.

The study, conducted in December 1983, was recently re-evaluated and confirmed by other studies, in Canada and western Australia, for last week's meeting of the American Cancer Society.