A drug frequently used to treat breast cancer patients can cause the disease to spread to the lungs, results of a recent study show.
According to research published in the Proceedings of the National Academy of Sciences journal, the drug – known as paclitaxel – causes molecular changes that allow breast cancer cells to escape from tumours.
It then creates a favourable environment that promotes the survival and growth of cancer cells in the lungs.
Paclitaxel is a one of the drugs used for front-line breast cancer chemotherapy treatment in Kenya and the world over.
It is also among 11 cancer medicines that were recently subsidised by Pfizer under a partnership backed by the American Cancer society and Clinton Health Access Initiative aimed at increasing access to life-saving cancer treatment drugs in Africa.
The study was conducted in mouse models by researchers at Ohio State University.
Promotes cancer progression
The scientists used the animals to understand paclitaxel's role in spreading cancer from original sites (breast) to other body locations.
The research also included an analysis of data from women with breast cancer which suggested that findings from the mouse models could be relevant to cancer spread in humans.
“That chemotherapy can paradoxically promote cancer progression is an emerging revelation in cancer research. However, a molecular-level understanding of this devastating effect is not clear,” said Tsonwin Hai, the study's senior author and a professor of biological chemistry and pharmacology at the US university.
In the mouse study, the changes that occurred in both the tumour and lung depended on a gene called Atf3, which is usually turned on by stress.
In human data, the researchers found higher Atf3 in patients who had undergone chemotherapy for breast cancer than those who did not.
"This gene seems to do two things at once: essentially help distribute the 'seeds' (cancer cells) and fertilise the 'soil' (the lung)," Prof Hai said.
More work needed
She cautioned that much more work is required before extrapolating the findings in mice to human cancer treatment.
"At this point, what our study and the recent literature on chemotherapy taught us is that it is prudent to keep our mind open, realising that chemo can help treat cancer, but at the same time may increase the possibility of the spread of that cancer," she said.
According to the researchers, the findings of the study could help scientists improve on the drug by addressing the downsides whilst preserving its cancer fighting properties.
"It's possible there could be a treatment given in conjunction with the chemo that would inhibit this problem by dampening the effect of the stress gene Atf3," Hai said.
Breast cancer is the leading cause of cancer related deaths among women in Kenya.
Patients usually rely on effective chemotherapy drugs to fight the cancerous cells and ‘force’ the disease into remission.
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