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3 Different Cancer Types

When we screen someone for cancer, we are trying to catch the cancer that can be treated to prevent the person from dying early from that cancer. To understand why screening and treatment aren’t very straightforward, let’s talk about 3 different cancer types.

Check out Dr. Prasad’s article on this topic to understand how he, an oncologist, thinks about different cancer types. The idea is that some cancers are worth catching, but most may not.

The Cancer Conundrum Model

In the Cancer Conundrum Model, there are three types of cancer that humans experience:

  • Sleepers
  • Invaders
  • Saviors

1. The Sleepers

The Sleepers are indolent tumors that grow too slowly to kill you. They are unlikely to spread from the source organ to other body parts. Dr. Attia has referred to these as turtle tumors, which is different from the hares, which are rapidly spreading tumors.

We don’t care to catch these. They often don’t require treatment.

2. The Invaders

The Invaders are the invasive tumors. These are aggressive tumors that will spread rapidly throughout the body, even in the very early stages, before they are visible on any imaging or testing.

We also don’t want to catch these because there is simply no proper treatment for them. They will progress despite anything we throw at them.

3. The Saviors

The final category is intermediate tumors, which are the Saviors. These can potentially be deadly if not caught and treated early. We want to catch these exact kinds of cancers because our intervention can impact the patient’s life. Dr. Attia calls these the hares.

We want to catch these cancers as early as possible. Early intervention would likely mean a cure. And, of course, like all cancers, we want to prevent them whenever possible.

Screening for These Cancers

Imagine all of these cancers are colon cancers or breast cancers. When we do a colonoscopy or mammogram, the cancer will show up as a polyp in the colon or calcification in the breast.

When the suspected lesion is cut out, it will look identical under the microscope to the pathologist regardless of whether it’s a Sleeper, Invader, or Saviors. There is no way to tell from the mass itself how it will behave in the future.

Ideally, we don’t want to find the Sleepers or Invaders because any intervention here will be of little value and, perhaps, even harm. We want to catch the Saviors.

Modern Early Cancer Detection Tests

I’ve written about early cancer detection tests such as full-body MRIs and blood-based tests, referred to as liquid biopsies. These can only be of value if they find the Saviors, but it’s unlikely they would.

Let’s look at the data from cancer screening. It’s clear that we aren’t preventing all-cause mortality (referred to as OS or Overall Survival in research studies) or even cancer-related deaths (DSS—disease-specific survival). This means that most of the cancers detected early are NOT the Saviors—if they were, then our early intervention would increase someone’s longevity.

But if we catch mostly Invaders and Sleepers and treat them, the extra harm we’re causing would lead to more morbidity and mortality, lowering the survivability curve.

Number Needed to Diagnose

You can check out the website The NNT to roughly understand what NND would mean in a similar concept. The number needed to diagnose a cancer refers to the number of people who would need a screening test, a biopsy, or other interventions before 1 person would have a survival benefit from the screening test.

For mammography, for example, we’d have to screen 500 women to find 1 diagnosis that is treatable. That’s considered rather large.

It’s better for colonoscopies, requiring the screening of only 200 or so people for 1 proper diagnosis. Again, these are still quite large numbers.

If you consider someone who is at low risk of certain cancer, such as a young woman for breast cancer and a young man for colon cancer, screening that person will often result in far many more false positives. This means you would have to screen a ton more people to get 1 appropriate diagnosis (a high NND.)

When we consider newer tests like whole-body MRI or liquid biopsies, it’s important to consider that if they are done in individuals at low risk of cancer, then the chance of a false positive or unnecessary biopsy, surgery, and/or chemo will be much higher.

The Distribution of Cancer Types

If I had to guess, most different cancer types based on the Cancer Conundrum Model would be Sleepers. These are your mild prostate cancers and DCIS breast cancers. Let’s say 60%.

The Invaders would make up 20% of all cancers and will do whatever they want to do despite our best clinical efforts.

The Saviors make up maybe 10% of all cancers. These are the ones we can treat with very high success rates. Certainly, by catching them early, but also by treating them, such as in the cases of testicular cancer, cervical cancer, certain skin cancers, Hodkin’s Lymphoma, certain NHL, and bladder cancer.

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