Intro: This is the first in a three- part series on cancer metastasis.
In this series, I’ll look at what dietary components contribute
to the spread of cancer, and what dietary interventions—
including specific foods—that may lessen the risk of cancer spreading,
thereby increase the chance of survival. Let’s go find out.
"What Causes Cancer to Metastasize?"
Metastasis formation is the leading cause of death in cancer patients.
That’s how most people die of cancer.
It’s not the primary tumor, but the cancer spreading through the body.
“[It’s] estimated that metastasis is responsible for [90 percent]
of cancer deaths”, with little progress made in stopping the spread
despite our modern medical armamentarium.
In fact, we can sometimes make it worse: Therapy-Induced Metastasis.
All the typical cancer treatments, radiation, chemotherapy, surgery—
even just poking the tumors with fine needle biopsies—
have the potential to contribute to the problem.
I mean, you can imagine how cutting around a tumor,
severing the blood vessels, might lead to the
migration of residual tumor cells. But why chemotherapy?
How might chemo exacerbate metastases?
Despite reducing the size of primary tumors, chemotherapy
can change the surrounding tissues, resulting in an increased
escape of cancer cells into the blood stream.
Sometimes chemo/surgery/ radiation are entirely justified,
but sometimes these treatments can make things worse.
If only we had a way to treat the cause of the cancer spreading.
The development of antimetastatic therapies has been hampered
by the fact that we haven’t been able to identity
the cells that initiate metastasis.
But then, this landmark study was published.
Researchers found a subpopulation of human cancer cells
“unique in their ability to initiate metastasis”,
all expressing high levels of a fat receptor known as CD36,
dubbed “the fat controller.”
It turns out palmitic acid or a high-fat diet specifically
boosts the metastatic potential of these cancer cells.
Where do you find palmitic acid?
Although originally discovered in palm oil,
it’s most concentrated in meat and dairy.
“Emerging evidence shows that palmitic acid . . .
serves as a signaling molecule regulating the progression
and development of many diseases at the molecular level”,
and that’s the saturated fat that is recognized by the
CD36 receptor on the cancer cells.
And we know that’s to blame, because if you block the CD36 receptor,
you block the metastases.
Now this was for a human cancer, however it was a human cancer
implanted into mice, but clinically (meaning in cancer patients)
the presence of these CD36-studded metastasis-initiating cells
does indeed correlate with a poor prognosis.
For example, CD36 appears to drive the progression of brain tumors.
If you look at the survival curves, those with tumors with less
CD36 expression lived significantly longer.
The same with breast cancer mortality.
No surprise, since “CD36 [appears to play] a critical role in
[the] proliferation, migration, and… growth of…breast cancer cells”.
Inhibit CD36, and you can inhibit
“the migration and invasion of the breast cancer cells.”
Cancer cell migration and invasion before and after CD36 inhibition.
And not just in “human melanoma- and breast cancer-derived tumors.”
Now we suspect that “…CD36…drives ovarian cancer progression
and metastasis” too, since we can inhibit ovarian cancer cell invasion
and migration and block both lymph node and
blood-borne metastasis by blocking CD36.
We see the same kind of effect with prostate cancer.
Suppress the uptake of fat by prostate cancer cells,
and you can suppress the tumor.
This was all studied with receptor-blocking drugs and
antibodies in a laboratory setting, though.
If these metastasis-initiating cancer cells particularly rely
on dietary fat to promote the spread of cancer, why not just
block the dietary fat in the first place?
Cancer cells love fat and cholesterol.
The reason why fat metabolism may fuel cancer’s spread is because
there is so much energy stored in fat.
“Hence, … metastatic cells might take advantage of this feature
to obtain the high amount of energy that is likely to be required
for them to anchor and [set up shop throughout the body].”
“The time when sugar was considered as the major, if not only,
fuel to support cancer cell proliferation is over.”
There appears to be ”a fatter way to metastasize”.
No wonder “…high-fat [diets may] …play a crucial role in increasing the risk
of different cancer types, …[including] several advanced cancers.”
Okay, if dietary fat may be “greasing the wheels of the cancer machine”
might there be speciﬁc dietary regimens we could use
to starve cancers of dietary fat?
You don’t know until you put it to the test, which we’ll cover next.