The research, published in BMC Cancer, was conducted by a team based at Shahid Sadoughi University of Medical Sciences in Yazd and collaborating institutions, using records from the Iranian National Cancer Registry. The team analyzed 4,928 cases of Hodgkin lymphoma and 13,600 cases of non-Hodgkin lymphoma diagnosed over the four-year study window. To make the numbers comparable across years and populations, the researchers calculated age-standardized incidence rates, a statistical adjustment that accounts for differences in the age structure of the population, using the World Health Organization’s standard population as the reference. This adjustment matters because a country with a young population can show fewer raw cancer counts simply because fewer people have reached the ages at which cancer risk climbs steeply.

For Hodgkin lymphoma, a disease that typically originates in B lymphocytes and is strongly associated with Epstein-Barr virus infection in many regions, the age-standardized incidence rate rose from 1.4 per 100,000 people in 2014 to 1.59 per 100,000 in 2017. That may sound like a small shift, but in epidemiological terms a steady climb of this magnitude over just four years signals a genuine trend rather than random year-to-year fluctuation, particularly when the same direction of change appears across demographic subgroups. The rates were not distributed evenly across the country. Yazd province recorded the highest Hodgkin lymphoma rate in 2014 at 2.74 per 100,000, while Lorestan topped the national figures in 2017 at 2.50 per 100,000, both well above the national average.

Sex-based differences emerged clearly in the data. Among Iranian men, the age-standardized incidence of Hodgkin lymphoma climbed from 1.66 per 100,000 in 2014 to 1.89 per 100,000 in 2017, while among women the corresponding figures rose from 1.13 to 1.29 per 100,000. In other words, men carried roughly a fifty percent higher burden of the disease than women throughout the study period, a gap consistent with patterns reported in many other populations and one that researchers attribute to a complex interplay of hormonal, immunological, and environmental factors. The parallel rise in both sexes suggests that whatever is driving the overall increase operates broadly rather than within one group alone.

Non-Hodgkin lymphoma, which encompasses a large and heterogeneous family of B-cell and T-cell malignancies, showed both a higher baseline and a similar upward trajectory. The age-standardized incidence rate increased from 4.26 per 100,000 in 2014 to 4.54 per 100,000 in 2017, meaning that non-Hodgkin lymphoma struck Iranians at roughly three times the rate of its Hodgkin counterpart. The provincial extremes were striking: Yazd again recorded the highest rate in 2014 at 7.13 per 100,000, and Ilam province reached 8.13 per 100,000 in 2017, figures that approach levels seen in some high-income countries. As with Hodgkin lymphoma, men were disproportionately affected, with rates rising from 5.29 to 5.52 per 100,000 over the study period, compared with a range of 3.26 to 3.58 per 100,000 among women.

What sets this study apart from routine registry reports is its use of spatial analysis, a set of techniques borrowed from geography that ask whether disease cases are scattered randomly across a map or whether they cluster in ways that hint at shared environmental or social causes. The researchers employed geographic information system tools and computed Moran’s Index, a formal statistical measure of spatial autocorrelation in which values near zero indicate randomness and positive values indicate that neighboring areas tend to share similar disease rates. For Hodgkin lymphoma, the analysis detected statistically significant geographic clustering in 2014, with a Moran’s Index of 0.12 and a p-value of 0.05, and again in 2015, with an index of 0.14 and a p-value of 0.03. Intriguingly, this clustering dissolved in 2016 and 2017, suggesting that the geographic pattern of the disease was itself shifting during the study years.

For non-Hodgkin lymphoma, the spatial story was different. In most years the cases showed no significant clustering, but 2016 stood out with clear and highly significant geographic aggregation, marked by a Moran’s Index of 0.18 and a p-value below 0.001. A transient clustering pattern like this is exactly the kind of signal that motivates further investigation: it could reflect a localized environmental exposure, an outbreak of an infection known to trigger lymphoproliferative disease, changes in diagnostic practice concentrated in certain provinces, or simply variation in how completely the registry captured cases from different regions. The authors are careful not to overinterpret the pattern, but they emphasize that such geographic heterogeneity deserves systematic follow-up.

The rising trend itself invites several possible explanations, none of which can be confirmed from registry data alone. Improvements in diagnostic imaging, pathology services, and cancer registration could account for part of the increase, as better detection inevitably raises recorded incidence. Yet the consistency of the trend across both lymphoma types and both sexes over a short period keeps open the possibility of true changes in disease frequency. Internationally, non-Hodgkin lymphoma incidence has been linked to factors ranging from viral infections such as Epstein-Barr virus and HIV to immunosuppression, autoimmune conditions, pesticide exposure, and aging populations. Iran’s distinct regional patterns, with provinces such as Yazd, Lorestan, and Ilam repeatedly exceeding national averages, provide natural starting points for studies that could test environmental and infectious hypotheses directly.

The study’s authors describe lymphoma in Iran as a silent public health concern, a phrase that captures the way these malignancies accumulate burden without attracting the attention devoted to more common cancers. Their conclusion is a call for targeted public health interventions, particularly in the provinces where incidence runs highest, and for further research to clarify the risk factors underlying the geographic and demographic disparities the registry data reveal. Because the analysis rests on de-identified registry records and was approved by an institutional ethics committee, it demonstrates how routinely collected national health data, when combined with spatial statistics, can generate actionable intelligence at relatively low cost.

For the international cancer research community, the Iranian findings add a valuable data point from a Middle Eastern population whose lymphoma epidemiology has been less thoroughly documented than that of Europe or North America. The combination of rising age-standardized rates, a persistent male excess, and province-level hotspots paints a picture of a disease landscape in transition. Whether the upward slope of 2014 through 2017 has continued in the years since, and whether the fleeting clusters of 2015 and 2016 reappear in later data, are questions that only sustained registry investment can answer. What is already clear is that lymphoma in Iran is neither rare nor randomly distributed, and that the tools now exist to find it wherever it concentrates.

Subject of Research: Epidemiology and geographic clustering of Hodgkin and non-Hodgkin lymphoma in Iran based on national cancer registry data

Article Title: Epidemiology of hodgkin and non-Hodgkin lymphomas in Iran: shedding light on a silent public health concern

Article References: Ghafouri, A. H., Rahmanian, V., Hosseini, S., Hosseini, S. M. H., & Hazar, N. (2026). Epidemiology of hodgkin and non-Hodgkin lymphomas in Iran: shedding light on a silent public health concern. BMC Cancer. https://doi.org/10.1186/s12885-026-17101-z

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17101-z

Keywords: Hodgkin lymphoma, non-Hodgkin lymphoma, Iran, cancer epidemiology, age-standardized incidence rate, National Cancer Registry, spatial analysis, Moran's Index, GIS, public health, Epstein-Barr virus, geographic clustering