Why Doesn't Chemotherapy (docitaxel) Kill All Cancer Cells?

@denis76 asked ❝Still, I wonder why Chemotherapy (docitaxel) Doesn't Kill All Cancer Cells? Chemistry shoots sparrows from a cannon and misses? Right?❞

Not a scientist or physician, but the common rule of thumb is that there are about 1 billion cancer cells in each 1cm³ of tumour.

So it's more like shooting at a skyful of sparrows with grapeshot from a cannon. You'll definitely reduce the number of sparrows, but no matter how big the cannon is, you probably won't get all of them, and then the ones left will start reproducing again.

That's why triplet therapy pays off: ADT and ARSI attack the cancer cells in different ways than chemo does (it's like feeding the sparrows birth control as well as firing off cannons).

Some information from a couple of sources

Chemotherapy is highly effective at shrinking tumors, controlling disease progression, and prolonging life in men with advanced or metastatic prostate cancer. However, it is rarely curative for advanced cases and is primarily reserved for cancer that has spread to multiple parts of the body, rather than for localized, early-stage disease.
American cancer society

When treating advanced disease, chemotherapy is often combined with hormone therapy to improve outcomes. Its effectiveness varies depending on the specific situation: The Mayo clinic

As a patient who understands every prostate cancer tumor is different, I will offer the information that I've learned over the years.

Chemotherapy does not kill all cancer cells, because it targets rapidly dividing cells (affects the cell division process). However, prostate tumors often also contain slow-growing and/or dormant cancer cells.

Also, regarding the change in size of a PCa tumor after being treated with chemotherapy, my understanding is that a PCa tumor is composed of actual cancer cells and non-cancerous elements. For example, the percentage of cancer cells within a PCa tumor can range from 30% to 60% of the cell mass (that number changes depending on the doctor explaining). Therefore, even if all cancer cells within a tumor are killed, the prostate cancer tumor does not necessarily disappear from an ultrasound view, and especially not in the near term.

When the combination of ADT and ARSI treatments are used, they effectively force rapidly dividing cancer cells into a state of more slowly dividing or becoming dormant. As a result, the tissue supporting the previously rapidly growing cancer cells also reduces in size.

Just in case helpful, our longer-term hope for the systematic treatment of PCa is to leverage the developments in other types of cancer, which also seek to target the slow-growing and/or dormant cells.

Sometimes you really don’t know how many -or all - cells have been killed.
A friend had lung cancer which they treated with Keytruda.
After it shrunk the surgeon recommended removal. Surgical Pathology showed nothing but dead cancer cells - totally destroyed.
So perhaps yours is kaput, or perhaps as others have stated, the non-cancerous cells are still inside. I guess it will all come down to your future PSA results.
Phil

All Chemo's are poison that are designed to kill more cancer cells than normal cells. Radiation works on the same principal. There is no problem killing all the cancer cells with either. The problem is killing all the cancer cells while still leaving you alive at the end of the treatment. The lutamides and other hormone treatments do more to make the cancer cells dormant than actually kill them. Stop taking them and most of the cells will become active again.

There is no magic bullet that works for everyone. I have a friend that was given Keytruda and was hospitalized for 10 days since it attacked the kidneys (not even near the cancer). The warning on the commercials that it may kill you is true. Works for most, not all.

@jsh327

Das ist scheiße!
We're all **cked!

Oh man,
I can’t imagine chemo plus ADT drugs, can’t be very pleasant. I think if it was me I would just go with the ADT and forget the chemo, but thats just my humble non medical opinion. Quality of life must mean something.

Dave 3+4

@clevelandguy
The thing is chemo is almost always recommended when somebody has many metastasis that are way beyond being able to be treated with SBRT zapping, much less with ADT.

Many of those people are in pain from metastasis.

Chemo can definitely reduce a lot of the cancer with someONE that has a lot of of it. It can extend lives for many years.

The side effects of chemo vary considerably, Some people have minor discomfort others get very tired and find eating difficult. Most people for whom it is recommended it is well worth doing.t

@jeffmarc
The ones I have talked with did not enjoy it at all. Nausea,hair loss, mouth sores, ect. I have not heard of anyone that did chemo that had minor discomfort.

Dave 3+4

@northoftheborder

"That's why triplet therapy pays off: ADT and ARSI attack the cancer cells in different ways than chemo does (it's like feeding the sparrows birth control as well as firing off cannons)."

I LOVE your analogy 👍😂 !!!!