Chapter 77
Cancer — 4
The interactions between cancer and our gut microbiome play a pivotal role in our immune response. For example, when some patients with advanced, refractory solid cancers had a fecal microbiome transplant, it improved on the immunotherapy they were receiving. The totality of evidence to date strongly reinforces how critical our immune response is for preventing cancer’s ability to spread and colonize. Since our immune cells are less intact as we age (the jargon is immunosenescence), our health span is vulnerable. That’s why it is essential to keep our immune system at maximum strength—and when the earliest detection of cancer threat is manifest, no less when it is clinically diagnosed, we need to ramp it up.
THE HIGH-RISK PEOPLE NOW
The good news is that deaths from cancer have decreased, especially for breast cancer. In the United Kingdom, a study of more than five hundred thousand women with early invasive breast cancer showed a marked reduction in deaths from 1993 to 2015. Likewise, in the United States, the age-adjusted breast cancer mortality rate in 1979 was forty-eight per one hundred thousand women, which, in 2019, decreased to twenty-seven per one hundred thousand women, a 58 percent reduction. Much of this is ascribed to better treatment, since women who did not undergo mammography had improved survival, and there was no change in the contribution of screening over this extended forty-year period.
But the bad news is bad. New cases of cancer in the United States are on the rise, with over two million in 2023, and the trend is projected to continue. The rise is especially notable in young people, also documented in Europe and the UK, which alarmingly defies all we know about the predisposition of cancer with aging. Colon cancer is prominent now among young people (fig. 6.2). It is more likely to present in the late stages of the disease and involve the lower tract. It is the leading cause of cancer deaths in men under age fifty, and is the second-leading cause for women. People even in their teens and twenties are now presenting with advanced colon cancer.
Figure 6.2. Increase in colon cancer in younger age groups, United States. Adapted from “Bowel cancer is rising among young people,” Economist, September 28, 2023, https://www.economist.com/graphic-detail/2023/09/28/bowel-cancer-is-rising-among-young-people.
The increase in cancer among the young is also noted for breast, uterine, and genitourinary cancers, and among ages thirty to thirty-nine years. In the United States, seventeen of thirty-four types of cancer are on the rise in younger birth cohorts, of which nine had previously been on the decline. I wouldn’t be surprised if the root cause for some of this was, as suggested in the chapter on lifestyle+, high consumption of unprocessed foods, environmental carcinogenic exposures, or overuse of antibiotics. The latter may result from unintended alterations of the gut microbiome, with specific bacterial mutations that can help drive carcinogenesis. Half of the younger adults getting diagnosed with colon cancer are overweight; 17 percent are obese. Whether overweight or obesity contributes, or the other potential explanations mentioned are driving cancers in the young, remains to be resolved.