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Some 40 years ago physicians in the Middle East noted a high incidence and prevalence of upper small intestinal lymphoma.1–3 Later this condition was found to be associated with malabsorption as well as the presence of alpha heavy chain proteins.2–7 The disease was named by the WHO as “immunoproliferative small intestinal disease” (IPSID).6 One of the earliest reports of IPSID was from our centre.3,4 This study was designed to confirm the trend in the epidemiology of IPSID over the past 25 years in our medical centre. In a retrospective study (March 1974 to March 1999), we reviewed pathology reports from all surgical pathology laboratories in the province of Fars located in Southern Iran.
All reports, which were labelled as IPSID, were reviewed by one of the authors. Cases were grouped into five year intervals according to the date of the initial diagnosis and five year age groups. Age specific rates were calculated using midperiod population denominators for each age group, and summary age adjusted incidence rates were calculated by direct standardisation using the world standard population.8
During this 25 year period, more than 500 000 surgical pathology reports were recorded. There were 5421 gastrointestinal tract cancers of which 2326 (43%) were gastric cancers, 1398 (26%) colonic cancers 1161 (21%) oesophageal cancers, and 536 (10%) small bowel cancers. Of the small bowel cancers, 161 (30%) cases were IPSID. This composed 3% of all gastrointestinal cancers in this period.
Among the 161 IPSID cases, 98 (61%) were males with a mean age of 31.74 (SD 14.94) years and 63 (39%) were females (mean age 26.85 (8.88)). The standardised rate ratio (95% confidence interval) of males to females in the study was 1.39 (1.26, 1.69), which represents a higher incidence of IPSID in males. Almost all cases were village dwellers or those who had recently immigrated to large cities from their villages. Age specific rates and absolute frequency of IPSID in males and females are shown in table 1. The disease had its highest incidence in the third decade of life in both sexes. There has been a persistent decrease in the incidence of IPSID since 1986, as show in fig 1.
The sharp decrease in the incidence of IPSID in the period 1978–1983 coincided with the time of revolution and the Iraq-Iran war, which caused instability in all organisations. The incidence of IPSID has decreased over the past 15 years (r2 = 0.26, t (14) = −2.25, p = 0.04).
IPSID was once the most common small intestinal malignancy in the Middle East.1–6 Early infectious stress in infancy and chronic antigenic stimulation in the earlier part of life along with genetic factors are probably important in the pathogenesis of IPSID.7 In our series of 161 patients with IPSID, we observed a dramatic decrease in the incidence of the disease over the past decade.
After the Islamic revolution in Iran, improving sanitation in villages was one of the priorities of the many health strategies in Iran. Access to sanitary drinking water in rural areas increased from 35% before 1988 to 80% a decade later.9 Vaccination programmes increased dramatically after the Islamic revolution, reaching more than 90% of children.9 Local health facilities increased dramatically during the first two decades after the revolution.9
We postulate that improvement in health in general and decreasing childhood gastroenteritides in particular has resulted in a decrease in the incidence of IPSID. This report highlights the almost complete disappearance of a malignant disease from a region where it was once very common. This is probably related to changes in environmental factors, decreasing exposure to infectious agents.
Conflict of interest: None declared.
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