Smoking Is Linked With Increased Risk of Myeloproliferative Neoplasms

Smoking is associated with chronic, low-grade inflammation. One of many inflammatory cytokines that increased in those who smoke is tumor necrosis factor alpha, which upregulates nuclear factor kappa beta and facilitates clonal expansion in JAK2‐V617F—bearing cells.Smoking is also linked with chronic hypoxic hyperstimulation of myeloid cells. Both factors are also typical presentations of myeloproliferative neoplasms (MPNs).

A recently published cohort study with a register-based follow-up of some individuals from the Danish general population sought to investigate whether smokers are at an increased risk for developing MPNs versus those who have never smoked.

The study drew data from The Danish Health Examination Survey (DANHES), which includes basic healthcare information, provided on a questionnaire, for adults living in 13 of Denmark’s 98 municipalities. A total of 76,484 people—corresponding to 14% of the general population in these areas—provided responses between 2007 and 2008, and 75,898 were included in the final analysis. The total follow-up time was 518,977 person-years, and the mean follow-up time was 6.8 years (standard deviation, 0.9 years).

Among all women and men, 13.3% and 14.6%, respectively, were daily smokers. Another 34.4% and 40.5%, respectively, were either occasional or former smokers. A total of 70 new cases of MPNs were diagnosed during the follow-up.

The multivariable hazard ration (HR) of any MPN during the study period for those who smoked daily was 2.5 (95% CI, 1.3-5.0), and 1.9 (95% CI, 1.1-3.3) for those who smoked occasionally or who were former smokers. In terms of cumulative smoking, analysis showed an HR of 1.14 (95% CI, 1.06‐1.22, P = .0005) per 10 pack‐years of smoking versus those who had ever been smokers.

These findings, say the study’s authors, support the concept of smoking as an inflammatory stimulus that drives development of MPNs, and is consistent with other research that points to cellular similarities between the consequences of smoking and MPNs.

The study was limited by the fact that MPNs can be difficult to diagnose, and information provided in questionnaires was not verified by medical records, so some patients may have been misclassified.

However, conclude the authors, an increased risk of MPNs in smokers versus those who have never smoked was demonstrated, adding to the body of evidence suggesting that smoking is a risk factor in developing these malignancies.

Reference

Pedersen KM, Bak M, Sørensen AL, et al. Smoking is associated with increased risk of myeloproliferative neoplasms: a general population-based cohort study [published online October 14, 2018]. Cancer Med. doi: 10.1002/cam4.1815.