Common Comorbidities of Cancer and Their Underlying Causes
The chronic diseases that most often coexist in cancer patients are hypertension, hyperglycemia (diabetes), obesity with hyperlipidemia, heart disease, stroke (cerebral hemorrhage or infarction), anxiety disorders, and depression. I believe most oncologists share my intuition: after five years in oncology with more than a thousand outpatient encounters, we can readily draw this conclusion from patients' records.
Although the premalignant lesions of various cancers differ—chronic hepatitis B as a precursor of liver cancer, EBV infection as a precursor of nasopharyngeal cancer, *Helicobacter pylori* infection as a precursor of gastric cancer, and reflux esophagitis as a precursor of esophageal cancer—patients with different cancers share some common features: most also have the above physical and mental chronic conditions, and patients with these chronic diseases are also more prone to cancer.
We know not all premalignant lesions progress to cancer, and not all carriers of proto-oncogenes (such as BRCA1/2) develop cancer. Over half of Chinese carry *H. pylori*, yet only a few progress to gastric cancer; some gastric-cancer patients are not even *H. pylori* carriers, and the percentage of *H. pylori*-infected people who ultimately develop gastric cancer is only in the single digits.
Likewise, most hepatitis B patients never develop liver cancer or cirrhosis in their lifetime; only about one third do. BRCA1 or BRCA2 carriers also do not necessarily develop breast cancer.
So what causes some people to develop cancer? The medical consensus is that cancer results from the combined action of susceptibility genes, environmental factors, and bad habits—and these are not additive but multiplicative. Like a factored math problem, removing any one factor greatly lowers the probability of cancer.
Cancer is a multifactorial disease, and cancer patients mostly share these features: congenital oncogenes or acquired premalignant lesions (such as infection with hepatitis B virus, *H. pylori*, EBV, HPV, or HIV); carcinogens in their living or working environment; long-term life under toxic stress (for its nature and definition, see my article Let Toxic Stress Go to Hell); a diet favoring animal-source foods (fish, meat, eggs, dairy); lack of exercise or labor; excessive relational stress (including having too many or too few contacts, and strained relationships); a monotonous, dull life; lack of hobbies; and bad habits (such as smoking, drinking, binge eating, and favoring hot food and drink). Only when these factors act together does malignant transformation occur.
We now know that, apart from oncogenes and carcinogens, the other factors above are also the causes of hypertension, hyperglycemia (diabetes), obesity and hyperlipidemia, heart disease, stroke, anxiety disorders, depression, and other chronic diseases. So it is only natural that cancer patients develop these comorbidities.
Can cancer be reversed or cured? Yes! Some patients have shown us by their actual outcomes that cancer patients can survive for decades; the lucky ones can develop cancer in their fifties or sixties and live past a hundred. But these cancer patients have also all been reborn into new people. Among the cancer patients I currently see, Buddhist believers who receive proper treatment survive longer. The reason may relate to the vegetarian diet Buddhism promotes and the stabilizing effect Buddhist faith has on patients' emotions.
The chronic conditions above, including cancer, all relate to food intake. Professor T. Colin Campbell of Cornell University is hailed as the Einstein of nutrition; supported jointly by the American Institute for Cancer Research, the American Cancer Research Center, and China's CDC, he conducted decades of research on the relationship between nutrition and chronic diseases such as cancer.
The famous carcinogen dioxin was discovered by him. In a child-nutrition study in the Philippines, he also unexpectedly found that aflatoxin (a Group 1 carcinogen) paired with plant-source food does not cause liver cancer, but paired with animal protein sharply raises liver-cancer incidence. Professor Campbell's *The China Study* and *Whole: Rethinking the Science of Nutrition* are well worth reading; his conclusions rest on rigorous large studies supported by reliable epidemiological data, rather than on the airy guesses of some glib authors today. I believe most people, after reading Campbell's detailed reports, will be astonished; he advocates a diet centered on vegetables, fruit, and low salt.
Of course, Campbell's research is limited to nutrition and disease, which is not enough. Other common causes are also culprits in cancer and other chronic diseases: environmental factors, mental stress, and lifestyle. The severity of environmental pollution goes without saying; it is a major crisis of our age. Modern lifestyle habits are also unimpressive: too much animal-source food plus too little exercise makes many people obese and hyperglycemic.
The proportion of cancer patients with depression is also quite high. Cancer patients may have endogenous depression present before malignant transformation, or secondary depression—some become depressed after diagnosis. Depressed patients lack the will to live; under this negative emotion their habits change, and the body spontaneously generates mechanisms of chronic suicide, so it is no surprise that they develop incurable fatal disease.
China's current diagnosis rate for depression is not high; most depressed patients are never diagnosed in their lifetime. They silently endure this mental illness, struggling through life, or try to cure themselves; we often discover only after a person's suicide that he was tormented by depression. Public awareness of depression is also limited, so many cancer patients long suffered from depression before their cancer diagnosis without knowing it. Most oncologists do not understand depression and rarely consult psychiatrists or psychologists, so many cancer patients' depression goes unnoticed.
But my overall sense is that over half of cancer patients have depressive problems of varying degrees. I did not previously diagnose depression in the patients I saw, because I had not studied it much and did not use depression scales. So I do not yet have exact figures on what proportion of cancer patients are depressed or how severe it is, and the medical community has not paid enough attention. China's healthcare is still underdeveloped, people discriminate against mental illness, and psychological counseling is expensive, so most cancer patients do not get psychological help. In developed countries, cancer patients already have specialized counselors involved, but the famously high treatment costs also deter many.
As for anxiety, it may now be very common among Chinese people. My son told me about a phenomenon: in his class (a class of above-average top students in Haidian District, Beijing), apart from him, who grew up in a completely free environment, all his classmates grew up in oppressive family environments. Every child attends training classes and frantically drills problems, parents have high expectations, and few in the whole class are free of anxiety. The health problems of our next generation may be even more widespread; by general epidemiological patterns, the peak of chronic disease in China has not yet arrived.
I once read in Singapore's *Lianhe Zaobao* a report on a large epidemiological study showing that the generation born after World War II marks the peak of human health—their diet was healthier, their physical activity and labor greater, and chronic-disease rates lower; since then, humanity's overall health has been declining. The study showed that although modern human life expectancy is lengthening, the extra years are basically maintained in modern medical institutions on life-support systems, with no quality of life, merely adding suffering and burden to patients and families. We are now on this downhill slope; human physical and mental health is worsening from generation to generation.
The greatest benefit of studying and practicing medicine has been making me realize the importance of health and the reasons it is lost. Today I keep to several things: work, simple living, a light diet, labor, dialogue with the Buddha, cycling, study, gardening, reading, learning music, writing, and spending good time with loved ones, reducing all unnecessary socializing. I do most of them at a mediocre level, far from professional, but I enjoy them; it is just for my own pleasure, no need to be serious.
A few hundred years ago most humans lived as I do now; only after industrialization did humanity become a slave like a machine, gradually forgetting how to adjust body and mind. The result is streets full of modern humans with worried faces in a hurry, hospitals packed with patients even in corridor beds, and anxious relatives plus gloomy patients turning the doctors themselves into another kind of patient. Prison guards often tell inmates: you only stay in prison a few years, but we stay for life. Frankly, by the operating model of modern hospitals, patients are only "sick" for a while, while doctors are "sick" for life.
Modern life places an unbearable burden on body and mind, so it is no wonder modern diseases multiply. The root cause is that civilization has evolved too fast while humans themselves have evolved slowly; social evolution far outpaces human evolution, so humans cannot adapt. How to escape the pressure of this too-fast wave of evolution? The one permanent solution is—to ignore it.
Sometimes I lie on a patch of grass, squinting in the sun at the slow white clouds, wondering: did the Creator make us to sit countless exams, then spend our lives in an orderly routine job earning a living wage, endlessly depositing money we will never spend in a bank, clinging to this so-called security and ease, and living out our days satisfying our appetites and bodily desires?
My inner voice tells me no; the Creator made us to enjoy the pleasures of life. So I regard all the world's foolish rules and dogmas as nothing. I have decided to run my own life and to teach my child to do the same. So today, whatever I face, I keep an easy, go-with-the-flow attitude and do not force any outcome.