Time and space co-ordinates of Hodgkin's lymphoma in Sardinia, Italy.

Background: The epidemiological investigation of Hodgkin's lymphoma (HL) among the genetically peculiar population of the Italian island of Sardinia might provide interesting etiological clues.

Methods: We used the database of 1974-2003 incident cases of hematological malignancies in Sardinia and Bayesian methods to explore the time trend and geographic spread of HL incidence by sex, and age whether ≤44 or ≥45 years. We also tested its association with several socio-economic and environmental risk factors.

Results: The age- and sex-standardized (world population) incidence rate of HL was 2.6 per 100,000 (95% CI, 2.5-2.8). Over the study period, HL incidence increased linearly in both sexes and among those aged ≤44 years but not above that age Cases clustered among young women in a central-western area covering four bordering administrative units (13 cases 5.7 expected, = 0.002). The posterior probability of excess HL cases aged ≤44 years was elevated only in a commune in the suburban area of the region's capital. Cases aged ≥45 years were uniformly spread over the region. Among the risk factors we explored, urban residence was associated with an elevated and goat farming with a decreased risk of HL occurrence. We did not observe a link with socio-economic deprivation, environmental exposures, or multiple sclerosis. The geographic spread of COVID-19 was also unrelated to past HL incidence.

Conclusions: Our results prompt further in-depth investigation into the previously undetected cluster and the nature of the observed associations.