Why You Should Worry about Cancer Promotion by Diet as Much as You Worry about Cancer Initiation by Carcinogens

Many people are obsessed with avoiding carcinogens. But what makes cancers grow may be just as important as what gets cancer started. T. Colin Campbell and Thomas M. Campbell II argue that what food we eat can make a difference for how well cancer grows.

In this post, I don't want to put too much emphasis on the particular dietary danger they discuss; I mainly want to emphasize that what fuels the growth of cancer is just as important a question as what gets cancer started. Let me quote from Chapter 3, of their book The China Study: "Turning Off Cancer." First, on pages 40 and 41, they delineate three stages of cancer: initiation, promotion, and progression.

Cancer proceeds through three stages: initiation, promotion, and progression. To use a rough analogy, the cancer process is similar to planting a lawn. Initiation is when you put the seeds in the soil, promotion is when the grass starts to grow, and progression is when the grass gets completely out of control, invading the driveway, the shrubbery, and the sidewalk. So what is the process that successfully “implants” the grass seed in the soil in the first place—that is, initiates cancer-prone cells? Chemicals that do this are called carcinogens. These chemicals are most often the by-products of industrial processes, although small amounts may be formed in nature, as is the case with aflatoxin. ...

At this point in our lawn analogy, the grass seeds have been put in the soil and are ready to germinate. Initiation is complete. The second growth stage is called promotion. Like seeds ready to sprout blades of grass and turn into a green lawn, our newly formed cancer-prone cells are ready to grow and multiply until they become a visibly detectable cancer. This stage occurs over a far longer period of time than initiation, often many years for humans. It is when the newly initiated cluster multiplies and grows into larger and larger masses and a clinically visible tumor is formed. But just like seeds in the soil, the initial cancer cells will not grow and multiply unless the right conditions are met. The seeds in the soil, for example, need a healthy amount of water, sunlight, and other nutrients before they make a full lawn. If any of these factors are denied or are missing, the seeds will not grow. If any of these factors are missing after growth starts, the new seedlings will become dormant, while awaiting further supply of the missing factors. This is one of the most profound features of promotion. Promotion is reversible, depending on whether the early cancer growth is given the right conditions in which to grow. This is where certain dietary factors become so important. These dietary factors, called promoters, feed cancer growth. Other dietary factors, called anti-promoters, slow cancer growth. Cancer growth flourishes when there are more promoters than anti-promoters; when anti-promoters prevail, cancer growth slows or stops. It is a push-pull process. The profound importance of this reversibility cannot be overemphasized. The third phase, progression, begins when a bunch of advanced cancer cells progress in their growth until they have done their final damage. It is like the fully grown lawn invading everything around it: the garden, driveway, and sidewalk. Similarly, a developing cancer tumor may wander away from its initial site in the body and invade neighboring or distant tissues. When the cancer takes on these deadly properties, it is considered malignant. When it actually breaks away from its initial home and wanders, it is metastasizing. This final stage of cancer results in death.

Second, from pp. 46-48, some results of rat experiments:

Foci are precursor clusters of cells that grow into tumors. Although most foci do not become full-blown tumor cells, they are predictive of tumor development. By watching foci develop and measuring how many there are and how big they become, we could learn indirectly how tumors also develop and what effect protein might have. By studying the effects of protein on the promotion of foci instead of tumors, we could avoid spending a lifetime and a few million dollars working in the lab. ...

Animals starting with the most cancer initiation (high-aflatoxin dose) developed substantially less foci when fed the 5% protein diet. In contrast, animals initiated with a low-aflatoxin dose actually produced substantially more foci when subsequently fed the 20% protein diet. A principle was being established. Foci development, initially determined by the amount of the carcinogen exposure, is actually controlled far more by dietary protein consumed during promotion. Protein during promotion trumps the carcinogen, regardless of initial exposure. ...

The most significant finding of this experiment was this: foci developed only when the animals met or exceeded the amount of dietary protein (12%) needed to satisfy their body growth rate. That is, when the animals met and surpassed their requirement for protein, disease onset began.

It is very difficult to reduce exposure to carcinogens to zero. So most of us have or have had cells with the potential to bloom into cancer. The decisive difference between getting full-blown cancer may come from providing cancers with an abundance of their favorite nutrients. We had better get the research done to figure out exactly what is most nutritious to cancer. It is especially valuable if we can identify nutrients that are much more important to cancer than to the normal workings of the body. I discuss this idea more in these two posts:


Don't miss these other posts on diet and health and on fighting obesity:

Also see the last section of "Five Books That Have Changed My Life."