The American Cancer Society wants more Northwesterners to sign up for the latest phase of a sweeping study.

The study is part of a decades-long investigation that so far has established the link between smoking and cancer — and how diet and exercise affect the disease.

The American Cancer Society is hoping to sign up about 300,000 people across the country.

But of the 1,200 they were hoping for in the Portland area, only about 300 have volunteered so far.

Principal investigator Alpa Patel says they hope to identify subtle differences in lifestyles and behaviors that increase a person’s risk of cancer. They’re also looking for genetic predispositions.

“So we will be collecting a small blood sample on our participants at the time they enroll so that we can better understand that interplay between genetics and lifestyle,” Patel says.

The study is scheduled to run 20 years. Volunteers go through a one-and-a-half-hour interview to start with and then fill in a survey every couple of years or so.

On the Web:

http://www.cancer.org/research/researchtopreventcancer/participate-cancer-prevention-3

http://cps3portland.org

This story originally appeared on Oregon Public Broadcasting.