Why do some cancer treatments fail?

March 24, 2020 / / - Cancer treatment can take many different ways to kill tumor cells or control them.
ideally, they can cause tumors to shrink, but they can also be considered successful if they prevent them from growing.
but unfortunately, the impact will not last forever.
, a drug can have an initial effect on the size or growth of a tumor, but then, despite treatment, the tumor begins to grow again.
this is called drug resistance.
It's a reality that at least some patients' tumors will eventually become resistant to them, no matter what amazing new treatment we come up with," said Dr Georgina Sava, an assistant researcher on breast cancer resistance at Professor Simak Ali's lab at Imperial College London in London.
Sava is trying to predict how resistance could develop into a new drug, aiming to take action one step ahead of cancer.
says drug resistance is a big problem for cancer, and many people are trying to understand how and why it happens.
image Source: LRI EM Unit resistance is due to defects in cancer cell DNA.
we've talked on our blog about how cells start to cancer.
that the same process can help cancer evolve and adapt to treatment.
changes may mean that cells no longer respond to cancer drugs such as chemotherapy, targeted anti-cancer drugs or hormone therapy.
cancer cells can evolve cancer cells from normal cell development because of errors in key parts of our DNA.
but it doesn't stop there.
even if a cell becomes cancerous, DNA defects continue to occur.
some of these defects can make cells resistant to treatment.
cells in the tumor may have different DNA defects, so not every cancer cell in the tumor is exactly the same.
that's the problem.
"Treating cancer cells with medication is like survival for the fittest," Sava said.
ideally, every cell in the tumor would be killed.
, even if a cell happens to be resistant to the drug, it will survive and eventually grow into a new tumor.
"This is problematic because it is difficult to detect any residual drug-resistant cells, especially when they are rare."
Sava added: "Once drug-resistant tumours develop in this way, drugs that once reduced tumors will no longer be effective.
does the "drug" fail? Cancer cells are resistant to drugs in many ways.
Sava highlights the drug resistance of hormone therapy, a treatment for breast cancer caused by estrogen.
estrogen interacts with estrogen-like estrogen on the surface of breast cancer cells, signaling growth.
hormone therapy works by blocking this interaction or lowering estrogen levels in the body.
, however, if cancer cells develop specific defects in the estrogen-infested body, they become resistant to these therapies, meaning that cancer cells no longer need estrogen to signal division.
this happens, hormone therapy will no longer be effective.
with other drugs, such as chemotherapy.
cancer cells can develop many different defects, helping them avoid the effects of chemotherapy.
this includes changes in DNA: first stop the drug from entering the cells; pull them out before treatment can cause any damage; and help the cells quickly repair the DNA damaged by chemotherapy.
like Sava are trying to overcome drug resistance.
"One of the main ways we can try to overcome drug resistance is through the use of combined therapy."
" Sava says cancer cells are less likely to escape by using different drugs that fight cancer cells in multiple ways at the same time.
source: But it will also help predict how treatment may stop working, which is exactly what Sava is targeting breast cancer for.
Sava exposed breast cancer cells to the drug for a long time, mimicking the patient's medication.
" cells initially stop growing and die.
but after a few months of treatment, they start to grow again, and we can see that they are resistant to the drug.
, we can compare these drug-resistant cells with those that were initially drug-sensitive to find out how they adapted to become resistant.
Sava's study, she found that drug-resistant cells have begun to produce a cell pump called p-glycoprotein, which protects cells by blocking the drug's entry.
researchers have studied drug resistance for almost as long as they have used cancer drugs.
to make cancer drugs more effective, scientists like Sava need to find ways to overcome resistance.
we are increasing awareness of drug resistance, which paves the way for better treatment of patients," Sava said.
() Reference: Why do some cancer treatments stop working? 2. Novels general of drugs may overcome drug-resistant cancer cells.