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New Study Confirms Chemotherapy causes Cancer 


Mutations in the human body occur due to the use of chemotherapy and radiation in the mid and long terms.

Scientists at the Institut de Recerca Biomèdica of Barcelona have characterized, for the first time in human tissue, the genetic alterations caused by six therapies used for the treatment of cancer. Five of the therapies were based on chemotherapeutic drugs and one on radiotherapy.

The patterns of alterations identified in the study allow to evaluate the risk of mutations of each treatment, which opens a way to better understand its long-term side effects. The results are published today in the journal Nature Genetics.

Chemotherapy involves the use of drugs that interfere with the cell cycle, which in many cases causes the destruction of cancer cells. Among the surviving cells, and in their descendants, genetic mutations usually accumulate.

One of the characteristics of the treatment is that it is not very specific and affects both cancerous and non-cancerous cells. Therefore, chemotherapies can contribute to tumor mutations, as well as to the patient’s healthy tissues.

This finding supports some of the long-term side effects caused by this treatment, researchers explained.

“Chemotherapies have side effects, like all treatments, and it is important to study them to improve them,” says researcher Núria López-Bigas, head of the IRB Biomedical Genomics Laboratory and associate professor at Pompeu Fabra University.

The genome of metastatic tumors of different types of cancer, obtained from the Hartwig Medical Foundation, of more than 3,500 patients was used for the investigation. Researchers also provided information on the treatments received.

Analyzing the DNA mutations of the tumors, a set of these could be identified with a very specific pattern, according to López-Bigas.

Using these specific “traces”, scientists estimated the contribution of chemotherapies to the set of mutations of these tumors when compared with the mutations of the natural aging process.

In conclusion, chemotherapy contributes to tumor mutations and to those produced in the patient’s healthy tissues.

The patterns of mutations found included some previously determined in previous research. “It is very good that the same pattern is recovered”, scientists say.

“It gives us great confidence to know that what is detected is correct,” says Lopez-Bigas. The previous experiments used cell cultures in the laboratory while in this research human tissues are used.

Because chemotherapy is a treatment that affects both cancerous and non-cancerous tissues, researchers reasoned that analyzing the metastasis of patients provided the opportunity to identify the mutational footprint also for the other tissues.

According to López-Bigas, it is logical to think that the mutations identified in the metastatic samples can also occur in the rest of the cells.

“If the DNA is affected in the tumors there is no reason to think that other tissues will not be affected. The next step would be to measure it in healthy tissue,” says the researcher.

Metastasis samples also allowed to better identify mutations due to the behavior of their cells. “In the rest of the tissues it would be difficult to analyze the DNA because each cell has private mutations that are below our detection limit,” says the researcher.

The results of the research will contribute, according to the authors, to a better understanding of why side effects in cancer treatments take effect.

“Until now we had not been able to calculate the mutations. This is a step towards understanding the appearance of late side effects,” explains López-Bigas.

According to the researcher, the long-term objective is to know the effects that chemotherapy and other treatments have on the DNA of the cells in order to be able to correctly decide which are the appropriate doses in each case.

How do cancer cells communicate?

Long before cancer causes a metastasis, it prepares the ground in other organs. It does so by releasing substances that create the right conditions so that metastatic cells can nest.

In the case of pancreatic cancer, for example, the soil is prepared in the liver. Towards there the primary tumor sends small capsules called exosomes.

But what exactly do the exosomes in the liver do to create an environment conducive to tumor cells? According to María Abad, from the Institute of Oncology of Vall d’Hebron Hospital in Barcelona, “the key may be in the micro peptides, which are very small proteins”.

Formed by less than one hundred amino acids, compared to the hundreds or thousands that have the most known proteins, they seem to be of enormous importance in the functioning of the human body but so far they have been ignored because it was not known how to study them.

The researcher has begun to analyze blood and tumor samples from hundreds of patients with pancreatic cancer in search of micro peptides that have an important role in the evolution of the disease.

The project will apply proteomic techniques to find the micro peptides secreted by exosomes. “We think that micro peptides are a mechanism of communication between cells,” says Abad.

The objectives of the project are, on the one hand, to understand the role of micro peptides in the progression of pancreatic cancer. On the other, to improve the diagnosis and treatment of the disease, either by detecting the micro peptides that circulate in the blood or by developing drugs that block them.

“We started with pancreatic cancer because there is a great need to improve your treatment,” explains the researcher. But, “if we show that micro peptides are important in pancreatic tumors, they will also be important in other types of cancer.”

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About the author: Luis R. Miranda

Luis R. Miranda is an award-winning journalist and the founder & editor of The Real Agenda News. His career spans over 23 years in every form of news media. He writes about environmentalism, education, technology, science, health, immigration and other current affairs. Luis has worked as on-air talent, news reporter, television producer, and news writer.

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