What's Actually Modifiable
~40% of cancers are preventable
The American Cancer Society estimates 42% of US cancer cases and 45% of cancer deaths come from POTENTIALLY MODIFIABLE risk factors. That's a large fraction — and these are the ones you can actually do something about today, not wait for future therapies.
The modifiable risk list
Tap each factor to see its approximate contribution to US cancer burden.
This step is interactive — open the Thier app to try it.
Alcohol is bigger than most people think
Even moderate drinking (1 drink/day) measurably increases breast, colon, oesophageal, and liver cancer risk. The 2021 WHO position: there is no safe level of alcohol consumption with respect to cancer. This is dose-dependent — less is better, none is best — but the cultural acceptability of moderate drinking makes this the most under-recognised modifiable risk.
The infections people miss
HPV, Hep B, Hep C, H. pylori — four infections that together cause millions of cancers a year. All four are preventable (HPV + Hep B vaccines) or treatable (Hep C direct-acting antivirals, H. pylori triple therapy). Most primary-care systems screen for these only sporadically — ask.
Exercise — direct anti-cancer effect, not just weight
Exercise reduces cancer risk independently of body fat. Mechanisms: lower circulating insulin + IGF-1 (growth signals tumours exploit), lower estrogen exposure (relevant for breast + endometrial), better DNA-damage repair, immune surveillance via NK-cell recruitment. The 2019 Moore meta-analysis found leisure-time physical activity reduced 13 of 26 cancers by 10–42 % — the largest effect was oesophageal adenocarcinoma at –42 %.
Key Takeaway
The cancer playbook is 80% the same as the cardiovascular playbook: don't smoke, stay a healthy weight, exercise, limit alcohol — plus vaccinate against HPV + Hep B, treat H. pylori + Hep C if present, and protect from UV. Exercise carries a direct anti-cancer effect beyond weight management. These aren't small levers. They're the main story.