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Soya ‘killing’ women diagnosed with breast cancer

By Chukwuma Muanya, Assistant Editor   |   21 February 2017   |   4:50 am

Soy products…experts warn that women shouldn’t start consuming soya milk after a breast cancer diagnosis – because it may limit the effectiveness of treatment. PHOTO CREDIT: authoritynutrition.com

• Active ingredient limits effectiveness of treatment to tackle disease • Breath test detects aggressive tumours with 85% accuracy

It is considered a healthy alternative to dairy milk – and is famously popular among the yummy mummy crowd. But experts warn that women shouldn’t start consuming soya milk after a breast cancer diagnosis – because it may limit the effectiveness of treatment.

Tamoxifen could be inhibited due to soya’s active compound, genistein, interfering with the medicine’s action, a study found.Paradoxically, the naturally-occurring ingredient remains safe for women if it formed part of their diet before diagnosis, scientists claim.

Professor Leena Hilakivi-Clarke, of Georgetown Lombardi Comprehensive Cancer Centre, who conducted the biological pathway on rats, explained that timing of genistein intake is crucial.


“Oestrogen drives most breast cancer growth, yet high soya intake among women in Asian countries has been linked to a breast cancer rate that is five times lower than Western women, who eat much less soya,” she said.

“We have solved the puzzle in our rat model. See, while many oncologists advise their patients not to take isoflavone supplements or consume soya foods, our findings suggest a more nuanced message.

“Our results suggest that breast cancer patients should continue consuming soya foods after diagnosis, but not to start them if they have not consumed genistein previously.”

The study, which was published in the journal Clinical Cancer Research, could help patients improve the role that diet plays on their treatment.Lead researcher Dr. Xiyuan Zhang added that longtime sustained use of genistein before a diagnosis has a similar action to Tamoxifen.“It inhibits a mechanism called autophagy that would allow cancer cells to survive, which explains why it helps tamoxifen works,” she said.However, starting to consume it after breast cancer develops not trigger anti-tumour immune response to eliminate cancer cells when tested on rats.

Those consuming genistein as adults had a seven per cent chance of breast cancer recurrence after tamoxifen treatment, compared with a 33 per cent recurrence with rats exposed to genistein only after breast cancer developed.

Zhang added: “We do not know yet why this made the animals resistant to the beneficial effects of tamoxifen and increased risk of cancer recurrence.”

Also, a simple breath test could soon be used to detect two kinds of aggressive cancers. The test has proved successful in detecting stomach and esophageal cancers in 300 trial patients – with 85 percent accuracy. Both cancers tend to be diagnosed too late – at which point the chance of surviving five years is slim.

Experts claim this discovery by researchers at Imperial College London could be a game-changer for diagnosis and death rates. It could also save thousands from having to endure painful endoscopy exams, which involves forcing a tube down one’s throat to inspect their stomach.

“At present the only way to diagnose esophageal cancer or stomach cancer is with endoscopy,” lead researcher Dr. Sheraz Markar told the European Cancer Congress 2017 last week. “This method is expensive, invasive and has some risk of complications.”

“A breath test could be used as a non-invasive, first-line test to reduce the number of unnecessary endoscopies. In the longer term this could also mean earlier diagnosis and treatment, and better survival.”

The trial was based on the results of previous research that suggested differences in the levels of specific chemicals between patients with stomach or esophageal cancer and patients with upper gastrointestinal symptoms without cancer.


The new research aimed to test whether this ‘chemical signature’ could be the basis of a diagnostic test. In the new study, the research team collected breath samples from 335 people at three different London hospitals.

Of these, 163 had been diagnosed with stomach or esophageal cancer and 172 showed no evidence of cancer when they had an endoscopy.All the samples were analysed with a technique called selected ion flow-tube mass spectrometry, which is able to accurately measure small amounts of different chemicals in mixtures of gases such as breath.

Researchers measured the levels of the five chemicals in each sample to see which ones matched to the ‘chemical signature’ that indicated cancer.
The results showed that the test was 85 percent accurate overall, with a sensitivity of 80 percent and a specificity of 81 percent.This means that not only was the breath test good at picking up those who had cancer (sensitivity), it was also good at correctly identifying who did not have cancer (specificity).


In this article:
Leena Hilakivi-ClarkeSoya


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