IGF binding protein linked with colorectal cancer in older men

Elevated levels of insulin-like growth factor binding protein 3, or IGFBP3, were predictive of colorectal cancer among older men independent of both total IGF-I and conventional risk factors, study data show.

“Several studies have examined the association of IGF-I with cancer mortality; however, these investigations included small numbers of outcome events, and few studies have focused on IGF binding proteins,” Yi X. Chan, MBBS, of the School of Medicine and Pharmacology at the University of Western Australia, Perth, and colleagues wrote. “Prospective cohort studies in large homogenous populations are needed to clarify if IGF-I and its binding proteins are associated with risk of developing cancer.”

The researchers conducted a prospective cohort study of 4,042 men aged 70 years or older. Chan and colleagues measured the patients’ total plasma IGF-I, IGFBP1 and IGBP3 between 2001 and 2004, and measured cancer-related outcomes until June 20, 2013. The researchers performed analyses with proportional hazards models using death as a competing risk.

Over 9 years of follow-up, 907 men were diagnosed with cancer, Chan and colleagues reported. Prostate cancer comprised 359 of these, followed by colorectal (n = 139) and lung (n = 125) cancers.

Total IGF-1 was not linked with any of the three cancers after adjustment, Chan and colleagues wrote. However, the researchers reported that higher IGFBP3 was associated with an increased incidence of colorectal cancer (subhazard ratio = 1.2; 95% CI, 1.01-1.43) with each one standard deviation increase in IGFBP3. This association did not occur in any other cancers, according to Chan and colleagues, nor did it change when total IGF-I was included in the model (subhazard ratio = 1.28; 95% CI, 1.03-1.58).

“Higher IGFBP3 is independently associated with an increased risk of colorectal cancer in a cohort of community-dwelling men aged 70 years and above,” the researchers wrote. “This was driven by an increased risk of colon cancer within the first 5 years of follow-up. Further studies are required to validate these associations in other older populations, and mechanistic studies are required to investigate if IGFBP3 is acting as a causative factor or biomarker for colorectal cancer in this setting.” – by Andy Polhamus

Disclosures: The authors report no relevant financial disclosures.