For most of the last century, cancer has been explained almost entirely through the lens of the mutated cell — a rogue actor, broken by carcinogen exposure or bad genetic luck, growing uncontrollably against the body's wishes. That explanation isn't wrong. But it has always been incomplete, and a growing body of research — much of it well inside mainstream oncology, not outside it — is filling in the rest of the picture: the environment that mutated cell has to grow in matters just as much as the mutation itself.

An Old Idea With a New Name

The metaphor at the center of this is often called terrain theory, but its most useful formal version has a name and a date: the seed and soil hypothesis, proposed by British surgeon Stephen Paget in 1889. Paget was trying to explain a puzzle — why certain cancers metastasize to specific organs far more often than blood flow alone would predict. His answer was that a cancer cell (the seed) can only take root and grow in an organ environment (the soil) that's hospitable to it. Drop the same seed in inhospitable soil, and nothing grows.

That idea sat quietly for most of the 20th century while genetics dominated cancer research. It has come back with real force in the last two decades, as researchers have built out the concept of the tumor microenvironment — the ecosystem of immune cells, blood vessels, signaling molecules, and metabolic conditions surrounding a tumor that determines whether it thrives, stalls, or gets cleared.

Jason Fung and The Cancer Code

Nephrologist Jason Fung, known for his work on fasting and insulin resistance, applies this same seed-and-soil framework directly to cancer biology in his book The Cancer Code (2020). His central argument: the body likely produces abnormal or precancerous cells on a fairly routine basis over a lifetime, and a healthy immune system and metabolic environment identifies and clears most of them before they ever become a problem. Cancer, in his framing, isn't purely a story of a mutation appearing — it's a story of a mutation appearing in soil that's already compromised enough to let it take hold: chronically elevated insulin, systemic inflammation, and metabolic dysfunction that both fuels abnormal cell growth and blunts the immune system's ability to police it.

Fung leans particularly on the role of hyperinsulinemia — chronically elevated insulin, common in obesity and insulin resistance — because insulin and its related growth pathway, IGF-1, are potent growth signals that cancer cells are especially good at hijacking. This is not a fringe claim; the link between obesity, insulin resistance, and increased risk across multiple cancer types is well documented in the epidemiological literature. Fung's contribution is less a new discovery than a reframe — connecting dots that oncology and metabolic research have each documented separately, into a single, coherent story about terrain.

"One does not have to explain why the fire went out if one can explain why it never started." — a framing Fung uses to describe prevention through terrain versus late-stage intervention

This Isn't Actually "Alternative"

It's worth saying plainly: terrain theory and mutation theory are not rival explanations competing for the same territory. Modern oncology's own framework — the "Hallmarks of Cancer," first proposed by Douglas Hanahan and Robert Weinberg in 2000 and updated repeatedly since — explicitly includes tumor-promoting inflammation, immune evasion, and altered cellular metabolism (the Warburg effect, cancer's preference for fermenting glucose even when oxygen is available) as core, established features of how cancer develops and spreads. These are terrain concepts, sitting inside mainstream cancer biology, not outside it. The seed still matters enormously — but the field has already accepted that soil does too.

What "Supporting the Terrain" Actually Means

Stripped of buzzwords, terrain support means paying attention to the handful of systems that shape whether the body's internal environment favors cancer growth or resists it:

  • Blood sugar and insulin regulation — through diet composition, movement, and sleep, since chronically elevated insulin is one of the most well-supported growth signals cancer cells exploit.
  • Chronic inflammation — driven by factors like visceral fat, poor sleep, unmanaged stress, and diet quality, and directly implicated as a tumor-promoting condition in the mainstream cancer literature.
  • Immune function — since immune surveillance is the body's primary mechanism for identifying and clearing abnormal cells before they establish themselves.
  • Mitochondrial health — increasingly studied for its role in cellular energy metabolism and how damaged mitochondrial function relates to the metabolic shifts seen in cancer cells.
  • Elimination pathways — the liver, kidneys, and lymphatic system doing the unglamorous daily work of clearing metabolic waste and toxins that would otherwise add to the body's overall burden.

An Important Boundary

None of this is a replacement for oncology care, and it should never be presented to a patient as one. Terrain support is what happens in the space around treatment — nourishing the body's resilience before, during, and after conventional care — not a substitute for surgery, chemotherapy, radiation, or immunotherapy when those are indicated. The most accurate way to think about it: mutation theory explains the seed. Terrain theory explains why some soil resists it and some doesn't. A person navigating an actual cancer diagnosis deserves both — the seed addressed directly by their medical team, and the soil supported by the daily choices within their own control.

"I know that I know nothing." — Socrates