The trouble with treating cancer is that each type has its own quirks. The quirks of pancreatic cancer make it one of the most lethal. The survival period after diagnosis is only four to six months. The main reason is that treatment with drugs – chemotherapy, which has had some success in extending lives for patients with other cancers, fails in the case of pancreatic cancer.
The widely believed reason for this failure has been that in pancreatic cancer, the tissue that surrounds the tumour, called the stroma, blocks the delivery of chemotherapy drugs to the tumour. A new study, published in Cancer Cell, questions that logic. It shows that the stroma, instead of supporting tumour progression, inhibits it by activating body’s immune system’s attack on the tumour.
All tumours are composed of some cancer cells and mostly stroma. But pancreatic cancer is unique, only around 10% of the cells in the tumour are cancer cells. That is the least proportion among all cancer types. The remaining 90% is the stroma consisting of special cells known as myofibroblasts.
Taking clues from this distinctive property of pancreatic cancer, previous studies indicated that stroma can act as a physical barrier to the chemotherapy drugs. This finding created a slew of clinical trials for combining chemotherapy with “stromal depletion therapy”, that is, removing the stroma from the tumour.
However, these trials had to be stopped abruptly when patients receiving this combination therapy were found to have an accelerated tumour progression as compared to those that only received chemotherapy. The reasons for this disappointing result remained unclear.