Low doses of chemotherapy to ‘keep cancer under control’

Scientists hope the new treatment will be less damaging to patients. Picture: Contributed
Scientists hope the new treatment will be less damaging to patients. Picture: Contributed
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Keeping cancer at bay with frequent low-dose chemotherapy treatments might be more effective than trying to destroy it, a study has found.

The unconventional approach suggests that cancer patients may have a better chance of survival living with their disease while keeping it under control.

Current cancer treatments often involve aggressive treatment with high doses chemotherapy in an attempt to wipe out as many tumour cells as possible.

But complete eradication of cancer is rare, and the toxic side effects of chemotherapy can be highly destructive – not only leading to hair loss, nausea and extreme fatigue, but also crippling the body’s immune system or triggering anaemia.

Some experts believe high-dose chemotherapy may actually worsen cancer by exerting a natural selection pressure that helps drug-resistant tumour cells to become more abundant.

The new “adaptive therapy” (AT) strategy is designed to oppose the evolutionary forces that drive cancer resistance.

It involves adjusting drug doses to suit tumour response. Rather than trying to eradicate a tumour, the treatment seeks to stabilise it by deliberately allowing a small population of drug-sensitive tumour cells to survive.

A team of US scientists led by Dr Robert Gatenby, from the H Lee Moffitt Cancer Centre and Research Institute in Tampa, Florida, conducted tests using the chemotherapy drug paclitaxel to treat mice with two different kinds of breast cancer.

Standard chemotherapy initially shrank the mouse tumours, but as soon as the treatment stopped they grew back. Skipping doses whenever the tumour shrank was also ineffective and also resulted in eventual cancer progression.

Adaptive therapy – a high initial dose followed by progressively lower doses as the tumour responded – was much better at controlling cancer growth.

In fact the treatment was so effective that between 60 per cent and 80 per cent of the mice could be weaned off the drug completely over an extended period of time without suffering relapses.

During the experiment, magnetic resonance imaging (MRI) scans were used to monitor the animals’ progress.

Writing in the journal Science Translational Medicine, the researchers argued that conventional “maximum dose” chemotherapy fuelled the “evolutionary dynamics that permit unopposed proliferation of resistant tumour populations”.

Rachel Rawson, senior clinical nurse specialist from the charity Breast Cancer Care, said: “This is an exciting avenue to explore.”