Recap: How to Combat Colon Cancer | Dr. Andy Chan

Podcast: ZOE Science & Nutrition
Host: Jonathan Wolf
Episode Release Date: May 27, 2025

Introduction

In this episode of ZOE Science & Nutrition, host Jonathan Wolf delves into the rising concern of colon cancer, particularly its increasing prevalence among younger adults. To shed light on this critical health issue, Wolf is joined by Harvard Medical School Professor Dr. Andy Chan. Together, they explore the latest research on colon cancer, emphasizing the importance of early screening and dietary modifications to reduce risk.

Rising Incidence of Colon Cancer in Younger Adults

Dr. Andy Chan opens the discussion by highlighting alarming statistics from the American Cancer Society:

“The American Cancer Society just came out with a very sobering report that statistics are such that now the leading cause of cancer death in people younger than 50 among men is colon cancer” (00:42).

He explains that colon cancer rates have doubled among individuals under 50 since the 1990s and are projected to become the leading cause of cancer death for both men and women by 2030 (01:01). This shift marks a significant departure from the trends observed two decades ago.

Wolf acknowledges the surprising nature of these statistics, noting that colon cancer is set to surpass breast cancer in mortality rates for women under 50:

“Which I feel is... that there is not a popular understanding of just how common this is becoming as a cancer for younger people” (01:28).

Dr. Chan concurs, stating that gastrointestinal cancers, particularly colon cancer, are increasingly diagnosed at younger ages, a trend not as pronounced in other cancer types like breast cancer (01:44).

The Importance of Colon Cancer Screenings

Addressing the surge in colon cancer cases, Dr. Chan emphasizes the critical role of regular screenings:

“Screening is something that we know saves lives... most colon cancers in early stages are not symptomatic” (02:31).

He underscores that early detection through screening can lead to a cure rate of 90-95% with surgical intervention alone when cancer is identified at stage one or when large polyps are removed (03:29). This statistic highlights the life-saving potential of proactive screening.

Due to the rising incidence in younger populations, the recommended screening age in the U.S. has been lowered from 50 to 45 years. Additionally, individuals with a family history of colon cancer are advised to begin screenings earlier, either at 40 or a decade before a relative's diagnosis (04:48).

Screening Methods: Invasive vs. Non-Invasive

Dr. Chan outlines the two primary categories of colon cancer screening:

1. Invasive Screening (Colonoscopy):

   • Involves a medical procedure where a physician examines the colon using a flexible camera.
   • Requires bowel preparation and sedation.
   • Capable of detecting and removing polyps, thereby preventing cancer development (04:53).

2. Non-Invasive Screening (Stool-Based Tests):

   • Conducted at home by collecting a stool sample.
   • Tests for blood or DNA mutations in the stool.
   • If abnormalities are detected, a follow-up colonoscopy is recommended (06:30).

Dr. Chan points out that while stool-based tests are less effective at identifying polyps, they are highly effective at detecting cancers:

“The screening that you can do with just a bowel movement will pick up cancers at a very high rate” (06:42).

He advocates for the use of the screening method that individuals are most likely to complete, emphasizing that the effectiveness of screening programs hinges on participation rates.

Dietary Factors Influencing Colon Cancer Risk

Transitioning to prevention strategies, Dr. Chan discusses the impact of diet on colon cancer risk:

1. Red and Processed Meats:

   • Recognized as significant risk factors.
   • The International Agency for Cancer Research identifies red and processed meat consumption as having the most compelling evidence linking diet to colon cancer risk (08:32).
   • Processed meats like sausages, salami, and bacon are particularly implicated due to nitrates and preservatives (12:19).

2. Alcohol Consumption:

   • Potentially a linear risk factor, where increased alcohol intake correlates with higher cancer risk.
   • While the exact relationship is still being studied, minimizing alcohol consumption is advised (09:30).

“Trying to reduce alcohol intake is probably important to do... it’s becoming maybe more clear that it's probably a linear risk factor” (09:59).

3. Whole Grains and Fiber:
   • Emerging evidence suggests that diets rich in whole grains and fiber may offer protective benefits against colon cancer.
   • These dietary components positively influence the gut microbiome, which in turn may reduce cancer risk (10:32).

Dr. Chan elaborates on ongoing research aimed at tailoring diets to promote a healthy gut microbiome, potentially mitigating colon cancer risk through nutritional interventions (11:50).

Mechanisms Linking Diet to Colon Cancer

Delving deeper, Dr. Chan explains the biological mechanisms by which diet influences cancer risk:

• Nitrates and Preservatives:

  • Found in processed meats, nitrates may contribute to carcinogenesis, although the exact pathways require further investigation (12:19).

• Cooking Methods:

  • High-temperature cooking methods can produce heterocyclic amines, which are carcinogenic in animal studies.
  • Charring meat through grilling or frying is a concern for increased cancer risk (13:07).

• Gut Microbiome Alterations:

  • Diets high in meat can disrupt the gut microbiome, promoting dysbiosis.
  • Certain amino acids and proteins in meat may foster the growth of harmful bacteria that produce sulfur compounds, which are carcinogenic to colon cells (14:34).

Conclusion

Dr. Andy Chan's insights underscore the critical need for increased awareness and proactive measures in combating colon cancer, especially among younger populations. Regular screenings, early detection, and informed dietary choices emerge as pivotal strategies in reducing colon cancer incidence and mortality. As research continues to evolve, understanding the interplay between diet, gut health, and cancer risk will be essential in developing comprehensive prevention and treatment approaches.

Note: The episode concluded with an advertisement for the ZOE Health app, which provides consumers with real-time insights into the nutritional quality of their food through a simple photo feature. This section has been excluded from the summary as per the content guidelines.