High platelet count associated with increased risk for certain cancers
Individuals with an increased platelet count demonstrated an increased risk for cancer, with the association especially strong in colon, lung, ovarian and stomach cancers, according to a nested case-control study in JAMA Network Open.
Researchers also reported notable associations of elevated platelet count with esophageal, kidney, pancreatic and other gastrointestinal cancers. They described the associations as transient and most pronounced within 6 months of cancer diagnosis.
“A growing body of laboratory research has shown the direct involvement of platelets with cancer,” Vasily Giannakeas, MPH, epidemiologist at Women's College Hospital and PhD candidate at Dalla Lana School of Public Health at University of Toronto, told Healio. “We wanted to get a better understanding of the relationship between platelets and a new cancer diagnosis using a comprehensive epidemiologic approach. In particular, we wanted to determine what types of cancer were associated with an elevated platelet count and the timing of this association relative to a cancer diagnosis.”
Background and methodology
The analysis included 8,917,187 eligible Ontario residents (median age, 46.4 years; 55.8% women) enrolled in the provincial health insurance plan with a routine complete blood count test between 2007 and 2017.
Giannakeas and colleagues matched one case patient (individual with a new cancer diagnosis during the observation period) to three controls (individuals who had not been diagnosed with cancer before the date of the diagnosis of their matched case patients) according to sex, age and health care use patterns.
The researchers assigned both case patients and control individuals to one of five exposure groups, based on age- and sex-specific platelet count distributions in the control population. They estimated ORs for specific cancer sites for each category of platelet count at intervals up to 10 years after a blood test.
Among the individuals in the study, 495,341 (5.6%) received a first primary cancer diagnosis during the 10-year observation period. Results showed an OR of 2.32 (95% CI, 2.28-2.35) for a solid tumor diagnosis associated with a very high ( 90th percentile)vs. a medium platelet count in the 6-month period prior to diagnosis.
Additionally, individuals with a very high platelet count demonstrated increased risks for colon (OR = 4.38; 95% CI, 4.22-4.54), lung (OR = 4.37; 95% CI, 4.22-4.53), ovarian (OR = 4.62; 95% CI, 4.19-5.09) and stomach (OR = 4.27; 95% CI, 3.91-4.66) cancers.
“The differences in our findings by cancer type surprised me,” Giannakeas told Healio. “Clearly there is a mechanism on platelets that is occurring with certain cancer types but not with others, such as breast and prostate cancer.”
Giannakeas added that for many of the cancer types, the magnitude of association increased with increasing stage at diagnosis.
The findings suggest an elevated platelet count could potentially serve as a marker for the presence of some cancer type, researchers wrote.
“I hope our work has provided some additional understanding about the relationship between platelets and cancer,” Giannakeas said. “I would like to see if platelet count could be useful in the clinical setting as a risk-stratification tool for cancer. I do not see platelet count as a standalone screening measure, but perhaps it would be useful in combination with other screening modalities for early cancer detection.”
For more information:
Vasily Giannakeas, MPH, can be reached at Women’s College Research Institute, Women’s College Hospital, 76 Grenville St., Sixth Floor, Toronto, ON M5S 1B2, Canada; email: firstname.lastname@example.org.