MALIGNANT AND BENIGN-TUMORS IN PATIENTS WITH NEUROFIBROMATOSIS TYPE-1IN A DEFINED SWEDISH POPULATION

BACKGROUND. The development of malignant and benign tumors in patients with neurofibromatosis type 1 (NF1) was investigated in a long term f ollow-up study of 70 adult NF1 patients living in Goteborg, Sweden, on January 1, 1978. Their mean age at that time was 44 years (range, 20- 81 years). The 70 NF1 patients had previously been investigated in a p opulation-based study. METHODS. The first part of this study involved a cancer registry study. The authors compared the number of tumors in the 70 NF1 patients reported to the Swedish Cancer Registry during the period 1978-1989 with the number of tumors expected in the general po pulation by matching the incidence rates of the two populations specif ic to age, time of follow-up, and gender. The 95% confidence interval for the risk quotient between the risk to the patients and the risk to the general population was estimated. The second part of the study wa s a clinical pathologic follow-up study. All living patients were offe red a clinical reexamination in 1990. All hospital records for all the NF1 patients were reviewed, and death certificates were also reviewed when available. RESULTS. Malignant tumors were reported to the Cancer Registry four times as often in the NF1 patient group as in the gener al population (95% confidence interval, 2.1-7.6) during the follow-up period 1978-1989. Before 1978, 5 of 70 patients (7%) had 6 malignant t umors; these patients were not included in the Cancer Registry study. Using all available clinical data on the 70 NF1 patients from their bi rth up to 1990, the authors found that 17 of 70 patients (24%) had dev eloped a total of 19 malignant tumors, namely, 5 sarcomas (in 7% of pa tients), 13 carcinomas (in 16%), and 1 malignant melanoma (in 1%). Fou r pheochromocytomas (in 6% of patients), 2 adenomas, and 1 C-cell hype rplasia were diagnosed. Five gastrointestinal stromal tumors (in 7% of patients) were also diagnosed. CONCLUSIONS. Malignant tumors were rep orted to the Swedish Cancer Registry significantly more often in the N F1 patients than was expected in the general population matched for ag e, gender, and time of follow-up. The development of tumors is part of the NF1 disease process, and this deserves attention both in the clin ical setting and in family counseling dealing with complications of NF 1 in adulthood. (C) 1997 American Cancer Society.