Chemotherapy can backfire by helping healthy body cells to fuel treatment-resistant cancer and growth, research has shown.
The surprise discovery suggests that many forms of cancer treatment can actually make the disease tougher to tackle.
Almost all solid tumour cancers, such as those affecting the breast, prostate, lung and bowel, ultimately stop responding to chemotherapy.
Scientists now believe one reason why could be the effect the treatment has on healthy connective tissue cells called fibroblasts.
DNA-damaging cancer drugs cause fibroblasts to pump out growth molecules into the tumour micro-environment belonging to the WNT family of proteins, the study found.
High levels of one called WNT16B helps cancer cells to grow, invade surrounding tissue, and resist chemo treatment.
Working in the laboratory, scientists observed an up to 30-fold increase in WNT production in response to chemotherapy.
"Cancer cells inside the body live in a very complex environment or neighbourhood," said lead scientist Dr Peter Nelson, from the Fred Hutchinson Cancer Research Centre in Seattle, US.
"Where the tumour cell resides and who its neighbours are influence its response and resistance to therapy."
Blocking the treatment response of fibroblasts could improve the effectiveness of chemotherapy, say the scientists whose findings are reported in the journal Nature Medicine.
The team examined cancer cells from prostate, breast and ovarian cancer patients who had been treated with chemotherapy.
The Best Cancer-Fighting Foods
Carrots are rich in beta-carotene, a super strong antioxidant that helps keep stomach, prostate and lung cancer away.
Cabbages contain cancer-fighting indole-3-carbinol, which are said to help ward off cancer. Brocolli is a well-known cancer busting vegetable as its glucoraphanin enzyme protects the body from rectum and colon cancer.
Containing a rich source of antioxidant lycopene, they protect the body from various cancer cells, plus it's also packed with vitamin C, which helps strengthen the body's immune system.
Garlic isn't just a great way to flavor our food, but it's a clever way of incorporating a cancer-busting food into our diet. Garlic is proven to boost immunity, which helps our body fight against nasty cancerous cells. Chives, leeks and onions are also part of the allium vegetable group, which help reduce the risks of stomach, colon and prostate cancer.
Flax seeds contain a strong antioxidants called ligans which help keep cells healthy and safe from cancerous cells. They also contain Omega-3, which are believed to prevent colon cancer.
Rated as one fo the highest antioxidant foods, blueberries keep the body's cells healthy and full of oxygen, warding off cancerous cells attacking.