MEMORANDUM FOR: Science Writers and Editors on the Journal Press List

July 29, 1999 (EMBARGOED FOR RELEASE 4 P.M. EDT August 3)

Julianne Chappell, Executive Editor, Dan Eckstein, (301) 986-1891, ext. 119

Sunscreen Use Encourages Prolonged Sun Exposure

Young European adults who used a sunscreen with a sun-protection factor of 30 while on vacation spent more time in the sun than those who used SPF 10, according to a study reported in the August 4 issue of the Journal of the National Cancer Institute.

There are compelling data showing a strong relationship between duration of sun exposure and skin cancer, say the investigators, Philippe Autier, M.D., and associates at the European Institute of Oncology, Milan, Italy. Therefore, they write, people should be warned that using sunscreen may inadvertently prolong recreational sun exposure.

The higher the SPF of a sunscreen, the greater its ability to delay sunburns caused by sun exposure. However, while sunscreen does protect against sunburn, its use has been associated with increased risk of melanoma, basal skin cancer, and moles.

For their study, the authors recruited university students in France and Switzerland who were going on vacation in the summer of 1997. Forty-four participants were given tubes of sunscreen having an SPF of 10, while 42 received indistinguishable tubes containing sun block rated at SPF 30. The sunscreens differed only in concentration of active ingredients. No instructions were given concerning sun exposure or use of the sunscreens, and the participants did not know which sunscreen they had received. While on vacation, each person kept a daily journal detailing hours of sun exposure, amount of clothing worn, sunscreen applications, and sunburn or skin-reddening experience.

The two groups spent nearly equal time on vacation (19.4 days on average for SPF 10 and 20.2 days for SPF 30). The numbers of sunny days they sunbathed or took part in outdoor activities were also equivalent, as was the amount of sunscreen used. There was no difference in sunburn experience between the two groups. However, there was a marked difference in hours of sun exposure between them. Those receiving SPF 10 averaged a total of 58.2 hours of sun exposure on vacation, while those receiving SPF 30 averaged 72.6 hours, a 25% difference in exposure. Their journals also revealed that, as the holidays progressed, the users of SPF 30 tended to start sunbathing earlier than the SPF 10 users, resulting in more exposure during the middle of the day when solar intensity is at its peak.

Karen Emmons, Ph.D., and Graham Colditz, M.D., Dr. P.H., Boston, note that the findings of Autier and associates may help in interpreting previous studies that suggested that individuals who use sunscreen have higher rates of skin cancer than those who do not. The findings also highlight the need for people to use both sunscreen and other means of sun protection. Although skin cancer is largely preventable, the incidence of melanoma in the United States is increasing by 4% per year. Emmons and Colditz advise that it is time to implement prevention strategies at the national level.

Contact: Dr. Philippe Autier, Milan, Italy 39-02-574-89821; fax 39-02-574-89813. Editorial: Todd Ringler, Harvard, (617) 632-5357; fax (617) 632-5520.

BRCA2 Mutations Linked to Many Types of Cancer

Mutations of the BRCA2 gene, which are known to be associated with high risk for breast and ovarian cancer, have now been linked to increased risk for cancers of the prostate, pancreas, gallbladder and bile duct, and stomach, and malignant melanoma, according to a study published in the August 4 issue of the Journal of the National Cancer Institute .

The findings of this new study are presented for the Breast Cancer Linkage Consortium by Douglas Easton, Ph.D., and Deborah Thompson, M.Sc., Cancer Research Campaign, Cambridge, U.K.

Cancer risks were investigated in 173 families who have a member who tested positive for a breast or ovarian cancer-associated BRCA2 mutation or who have a clear linkage to such mutations. These families were identified at 20 medical research centers in Western Europe and North America. Occurrence of other cancers was determined in a cohort of 3728 individuals within these families, among whom 681 persons had breast or ovarian cancer and 3047 persons were either known mutation carriers, were first-degree relatives of known mutation carriers, or were first-degree relatives of breast or ovarian cancer patients. Three hundred thirty-three cancers (other than breast or ovarian) occurred in this group. Incidence rates of cancers among these 3728 people were compared to population-specific incidence rates, and relative risks (RRs) for carriers of the BRCA2 mutations were calculated.

Statistically significant increases in risks were observed for: prostate cancer, relative risk (RR) = 4.65; pancreatic cancer, RR = 3.51; gallbladder and bile duct cancer, RR = 4.97; stomach cancer, RR = 2.59; and malignant melanoma, RR = 2.58. The RR of prostate cancer for men below age 65 years was 7.33. Among women who already had cancer in one breast, the cumulative risk of developing cancer in the other breast by age 70 was 52.3%, and the risk of developing ovarian cancer was 15.9%.

This study, believed by the authors to be the largest yet conducted on BRCA2 families and carriers, provides strong confirmation of an increased risk for several cancers among mutation carriers. They also note that the types of cancers associated with BRCA2 mutations do not fit any obvious pattern.

Contact: The Cancer Research Campaign, United Kingdom, 44-207 487 3768; fax 44-207 935 1546.

Note: This memo to reporters is from the Journal staff and is not an official release of the National Cancer Institute (NCI) or Oxford University Press (OUP) nor does it reflect NCI or OUP policy. In addition, unless otherwise stated, all articles and items published in the Journal reflect the individual views of the authors and not necessarily the official points of view held by NCI, any other component of the U.S. government, OUP, or the organizations with which the authors are affiliated. Neither NCI nor any other component of the U.S. government nor OUP assumes any responsibility for the completeness of the articles or other items or the accuracy of the conclusions reached therein.



             
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