New blood test tracks cancer development

Scientists at the CRUK Institute at Cambridge University have managed to follow the progress of cancer in people by following traces of tumour DNA circulating in patients’ blood (ctDNA).

Importantly this also allows scientists to identify tumour changes and chemotherapy drug resistance (Nature).

The scientists followed 6 patients with advanced breast, ovarian and lung cancers over two years taking blood samples at regular points, and by looking for changes in the tumour ctDNA before and after each course of treatment, they were able to identify which changes in the tumour’s DNA were linked to drug resistance following each treatment session.

Using this new method they were able to identify several changes linked to drug-resistance in response to chemotherapy drugs such as paclitaxel (taxol) which is used to treat ovarian, breast and lung cancers, tamoxifen which is used to treat oestrogen-positive breast cancers and trastuzumab (Herceptin) which is used to treat HER2 positive breast cancers.

Dr Nitzan Rosenfeld one of the study authors, said: “Tumours are constantly changing and evolving which helps them develop a resistance to many of the drugs we currently give patients to treat their disease”.

“We’ve shown that a very simple blood test can be used to collect enough tumour DNA to suggest to us what parts of the cancer’s genetic code is changing and creating tumour resistance to chemotherapy or biologically-targeted therapies”.

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Beating cancer with chemotherapy and better drugs

The mythology of cancer sees many claims. One of which is that we are beating cancer due to earlier diagnosis and better drugs. Let us consider the available research on chemotherapy – for almost every cancer patient treated with drugs is still, inevitably, given at least one round of good old chemotherapy.

Available research evidence does indeed point to chemotherapy having a positive effect for some cancer patients.

Let’s start here:

(1) The Department of Oncology at North Sydney Cancer Centre in 2004 published a report evaluating chemotherapy over the years and concluded that ‘it only made a minor contribution to survival’. The figures they came up with were 2.3% in Australia and 2.1% in America. In Britain there are 320,000 people diagnosed with cancer a year. About 60 per cent have chemo (although some of these people do not actually have cancer and were misdiagnosed by mammograms etc). Being generous and assuming no misdiagnoses, that would mean that chemotherapy had an effect on about 3,600 people. I cannot tell you from the research whether ‘effect’ means they were cured or whether they reached 5-year survival, or what. Sorry, I didn’t find the research very clear on that point.

(2) Somewhat alarmingly, last year we had the report from the Fred Hutchinson Cancer Center in Seattle that concluded ‘Chemotherapy can cause cancer to return’. Note that they did not say, ‘we know cancer can return after chemo’, which is how Cancer Research responded to this study. They said CAUSE – apparently chemotherapy can cause healthy cells to produce a protein WNT16B and this is taken up by cancer cells – it helps them re-grow and even protects them from the next round of chemotherapy.

You may feel that all this misses an important point and that drugs have moved on – chemo is past it; old hat: Drugs like Tamoxifen, Aromatase Inhibitors and Herceptin are not really chemotherapy agents, and you’d be right. In 2012 a couple of reports shed some light on the current state of play.

(3) Firstly, one study (lead by Professor Carlos Caldas – reported in Nature) had Cancer Research all excited. A ‘landmark study’ from their Cambridge Institute showed there were 10 different ‘clusters’ of breast cancer types. ‘No longer does one size fit all’ they cried at CRUK. (It would be churlish of me to mention that CANCERactive have been saying that for ten years, but what the heck). In the future CRUK are suggesting they can more accurately develop treatments for each cluster. The problem at the moment is that there are only treatments for two of the clusters, the Tamoxifen/AIs one and the ‘HER-2 targeted therapy using Herceptin’ cluster. So here’s a real improvement: 2 out of 10 is better that 2.3 per cent.

(4) Unfortunately, the excitement was crushed somewhat when three research studies reported on the existence of Cancer Stem Cells at the heart of tumours. A couple of UK cancer centres (Bart’s Hospital and the Blizzard Institute, London) have even isolated these nasty little cells. Apparently, if you don’t kill them off, they can re-grow.

In one of the three studies (from the University of Texas South Western Medical Centre), there were statements such as ‘Cancer Stem cells are in charge of tumours’, and the lead researcher, Dr Louis Parada and the other researchers added, ‘In the past we have tried to get rid of the entire stew of cancer cells. But shrinking a tumour by 50% is irrelevant. No current drugs tackle cancer stem cells – but at least we now know what to go after’.

(5) We are by no means ‘against chemotherapy’ at Junk Science UK, we just think the mythology and the hype needs to be calmed down. Perhaps the final words should therefore go to Duke’s University Medical Centre in Carolina who in their 2012 report concluded that ‘Patients with cancer are largely being mislead into believing that the drug they are being offered is somehow going to cure them’.

Oh dear.

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