Gender and time differences in initial location and histological grade of non-Hodgkin's lymphomas in Southern Sweden.
In accordance with international data, non-Hodgkin's lymphomas (NHL) in the Southern Health Care Region of Sweden were more common in men than in women and there was an inreasing incidence for both genders in the 1980s and 1990s. A study of the years 1983 and 1992, i.e. the beginning and the end of a 10-year period, was carried out. Case records for 94% of all adults diagnosed in 1983 and 1992 (220 men and 171 women) were reviewed. The sites of the lymphomas and malignancy grade (Kiel classification) were recorded. Comparisons were made between the genders and between the two years studied. Among 170 men with nodal lymphomas, 49 were localized (stage I-II) in lymphoid tissue regional to the respiratory tract, 18 were localized elsewhere and 103 were generalized (stage III-IV). The corresponding sites in 138 women were 28, 33 and 77, respectively (p = 0.002), implying a predominance of stage I-II lymphomas regional to the respiratory tract in men and a larger number of localized lymphomas elsewhere, mostly abdominal retroperitoneal with or without inguinal engagement in women. High-grade nodal lymphomas were more common in 1992 (54%) than in 1983 (34%, p = 0.01). suggesting an increasing number of mainly high-grade lymphomas. For extranodal lymphomas (50 in men and 33 in women), no clear differences were observed for gender and the years studied. Risk factors, e.g. occupational hazards, are probably different for men and women. The gender differences in initial nodal location suggest that initial lymphoma sites may be related to different risk factors. Epidemiologic studies where both malignancy grade and initial lymphoma locations are taken into account may be helpful in defining risk factors.