The death of actor Chadwick Boseman from colon cancer has led to increased awareness of how this cancer affects younger people. Boseman was diagnosed with colon cancer at age 39; he was only 43 when he died last month.
When do people normally develop colorectal cancer?
The vast majority of colorectal cancers occur among people ages 50 and older — about 90 percent — and risk increases with age. But new cases have been rising among younger adults and it has become a growing area of research. One recent study estimates the rate of new colorectal cancers among younger age groups will increase by 90% (colon) and 124% (rectum) by 2030.
How can we reduce our chances of developing colon cancer?
For colorectal cancer overall, AICR research reveals that people can reduce their risk through diet, staying a healthy weight and physical activity. It is unclear whether these same lifestyle risk factors apply to younger people, says Christine L. Sardo Molmenti, PhD, MPH, Cancer Epidemiologist and Assistant Professor at the Zucker School of Medicine at Hofstra/Northwell and Feinstein Institutes for Medical Research at Northwell Health. Molmenti of Northwell Health, is an expert in early onset colorectal cancer and wrote about the topic last year for AICR.
Here, Molmenti shares the latest research about lowering the risk of young-onset colorectal cancer.
Is the type of colorectal cancer diagnosed in a 30 or 40 year old different than that of an older person?
There is some indication that the molecular profile of early onset colorectal cancer is somewhat different. Evidence is pointing towards a potentially more aggressive tumor type, however the predominant concern is that patients are not getting diagnosed at an early stage. So, by the time they are diagnosed, the cancer is more likely to have reached a more advanced stage, which is associated with poorer prognosis and survival.
It seems there are two components at play: one, the histology is perhaps different and two, the delay in diagnosis.
Can you talk about the increasing trends?
Colorectal cancer is the third leading cause of cancer-related death in the US and the third most common cancer. New cases have been largely decreasing among adults ages 50 and over, but increasing among all groups of adults under 50. The majority of young onset cases are between 40-50 years of age. However, the sharpest rise is expected among 20 to 34 year-olds. An important difference is that left-sided colon and rectal cancers are more likely in the younger age group.
Could the increase be due to more testing among younger adults?
The evidence supports the fact that the rate is actually rising. The uptick started around 1974 and has gradually increased over time. In the last 5 years or so we have seen a dramatic increase in research and scientific publications related to the early onset of colorectal cancer.
There are many lifestyle factors AICR research links to colorectal cancer risk, such as obesity. How does BMI relate to this cancer among younger people?
Obesity in the US has increased in parallel with the rise of young-onset colorectal cancer – but we still do not know enough to definitively conclude that obesity is causally associated with early onset colorectal cancer. There is a correlation; they are both rising in parallel, but that does not equate to a causal association.
An analysis of a large group of nurses observed that obesity was associated with early onset colorectal cancer among women, but not men. Other studies have suggested that obesity may be a risk factor but this is still under investigation.
High amounts of red meat, processed meat and alcohol all increase risk. How do these, or other factors, link to early onset colorectal cancer?
We carried out a literature review and found that in a limited number of case control studies, red meat, processed meat and deep fried foods appear to be risk factors and certain fruits and vegetables may lower risk. More research is clearly needed in this area.
The role of alcohol, dietary patterns and smoking are still uncertain. Typically, colorectal cancer is a slow-growing tumor, developing over 10 to 20 years. There is some question and uncertainty about the duration of exposure and the threshold required to see an effect among younger people. Thus, for someone diagnosed at age 30, how many years did it take for the tumor to start growing, and how did the dose and duration of their exposure to risk factors play a role? This remains to be determined.
We recently conducted a study among patients under 50 who had a colorectal adenoma removed and evaluated their various lifestyle characteristics. Colorectal adenomas are the precursor to the majority of colorectal cancers. Compared to patients 50 years of age and older, the under 50 population had higher smoking rates, greater intake of red meat, and total fat. They also had a more pro-inflammatory diet. [Results of this study will be published this fall.]
To our knowledge, this is the first study to assess these lifestyle factors among young people who have had a colorectal adenoma removed.
And physical activity, does that influence the risk of developing colorectal cancer?
In our analysis, there was no significant link to physical activity, yet there is strong research-based evidence that physical activity lowers colorectal cancer risk in general.
The US Preventive Services Task Force recommends adults at average risk start getting screened at age 50. Are there any known factors that put a person at high risk for early onset colorectal cancer?
Yes, if you have a first-degree relative (parent, sibling or child) diagnosed with an advanced polyp guidelines recommend starting screening at age 40. If the relative was diagnosed with colorectal cancer, the same guidelines apply. My colleagues and I recently published on this very topic to increase awareness among patients, and health care providers.
There are other risk factors that also increase the risk, such as inflammatory bowel diseases. Few people are aware of the urgency.
You can read more here about the research related to lifestyle and colorectal cancer risk.
The CDC has screening guidelines and non-modifiable colorectal cancer risk factors.