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Overcrowded households, gender may affect incidence of Hodgkin’s lymphoma subtypes
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Children and young adults who live in overcrowded conditions appeared less likely to develop the nodular sclerosis subtype of Hodgkin’s lymphoma, according to study results presented at the European Cancer Congress.
However, overcrowding increased the risk for the “not otherwise specified” subtype of Hodgkin’s lymphoma, results also showed.
“Our findings related to the nodular sclerosis subtype may suggest that the recurrent infections to which children living in overcrowded conditions are likely to have been exposed stimulate their immune systems and hence protect them against developing this type of cancer later in their childhood and early adult life,” Richard McNally, MD, a reader in epidemiology at the Institute of Health and Society at Newcastle University, said in a press release. “Those who have a genetic susceptibility to Hodgkin’s lymphoma and have been less exposed to infection through not living in such over-crowded conditions may have less-developed immune systems as a result, and are, therefore, at greater risk of developing this subtype.”
McNally and colleagues used components of the Townsend deprivation score — including household overcrowding, non-home ownership, unemployment and households with no car — to evaluate how area-level socioeconomic deprivation impacted Hodgkin’s lymphoma incidence in a cohort of patients from northern England in the Northern Region Young Persons’ Malignant Disease Registry.
The analysis included 621 patients with Hodgkin’s lymphoma aged 0 to 24 years who were diagnosed between 1968 and 2003. The cohort included patients with the nodular sclerosis subtype (n = 247), mixed cellularity subtype (n = 105), lymphocyte-rich subtype (n = 58), “others” (n = 68) and “not otherwise specified” (NOS; n = 143).
Overall, more males had Hodgkin’s lymphoma than females (age-standardization rate [ASR] for males, 1.15 per million persons per year; 95% CI, 16.35-19.96; ASR for females, 10.52; 95% CI, 9.15-11.89).
However, the male–female ratio varied by age and disease subtype. For the nodular sclerosis subtype, there were 130 males and 117 females, but in the age 20 to 24 years age group, there were 72 women and 55 men (ASR for women, 18.79; 95% CI, 14.45-23.13; ASR for men, 14.26; 95% CI, 10.49-18.02).
“That this change takes place after puberty seems to suggest that estrogens may be responsible in some way,” McNally said in the release. “There are a lot of genes directly regulated by sex hormones, and they are obvious suspects. Alternatively, epigenetic changes … influencing key genes, induced by sex hormones, may be responsible.”
Increased house overcrowding appeared associated with a decreased incidence of nodular sclerosis Hodgkin’s lymphoma (RR = 0.88 for 1% increase in household overcrowding; 95% CI, 0.82-0.94). A 5% increase in household overcrowded halves the risk incidence of this sutype.
However, each 1% increase in household overcrowding increased the incidence of the NOS subtype (RR = 1.17; 95% CI, 1.09-1.25).
There was no effect of deprivation on incidence of mixed cellularity or lymphocyte-rich subtypes.
“We knew already that recurrent infections may protect against childhood leukemia, and now it looks as we can add Hodgkin’s lymphoma and, particularly, its nodular sclerosis subtype to the list,” McNally said. – by Anthony SanFilippo
Reference: McNally R, et al. Abstract 1414. Presented at: European Cancer Congress; Sept. 25-29, 2015; Vienna.
Disclosure: The researchers report no relevant financial disclosures.