Did you know that the same prostate can contain multiple cancerous areas, each with different types of cancer cells in them? Researchers have been trying to find out if this starts as a single type of cancer cell that spreads, changing as it goes, or if different cancer areas start of their own accord. And what they've discovered is raising important questions.
by Sophie Lutter
Last week, the journal Nature Genetics published the results of an Indiana Jones-worthy-quest to hunt down the holy grail of prostate cancer biology: how does prostate cancer start, and how do multiple different cancers start in the same prostate?
Scientists have known for a while that the same prostate can contain multiple cancerous areas, each with different types of cancer cells in them. What they haven’t known is whether this starts off as a single type of cancer cell that spreads out through the prostate, mutating and changing as it goes, or whether each of these different cancer areas starts of its own accord.
There were fewer explosions and plane crashes involved in this research than there may have been if Indiana Jones (or even just Harrison Ford, judging by recent events) was really involved, but a few unexpected plot twists meant that the results were no less surprising.
The team of scientists from different universities, including Professor Colin Cooper and Professor Ros Eeles at the Institute of Cancer Research and Professor David Neal at the University of Cambridge, looked at the prostates of three different men. For each man, they studied the sequence of the whole genome (the entire DNA sequence) of four cancer areas and one non-cancer area. All were taken from different parts of the prostate.
They found that even the non-cancerous parts of the prostate contained some of the same mutations as the cancer cells and that what looks like one cancer may contain many separate cancers in fused in a single mass.
This might mean that when prostate cancer starts, it isn’t just a case of a few cells going rogue and forming cancerous areas in an otherwise healthy prostate, but rather the whole prostate (or at least more of it than previously thought) going over to the dark side and becoming predisposed to turn cancerous.
This may have important implications for focal therapies for localised prostate cancer, which remove just the cancer, leaving the healthy parts of the prostate intact. In some cases, this can lead to fewer side effects than removing the whole prostate.
But this research suggests that if the whole prostate is indeed predisposed to becoming cancerous, it may be risky to leave parts of the prostate intact. However, while this research has raised some important questions and opened up some new avenues that we now need to explore further, this conclusion is not yet a done deal.
There’s still more work to do before we can say for sure what this research means for treatment of localised prostate cancer.
Professor Colin Cooper, first author of this research, said: “We need to look at more prostate cancer cases to see just how common it is for normal cells to share mutations with cancer cells. We also need to look at lots of separate non-cancer areas within the same cancer-containing prostate to try to map out the relationship between the normal cells and the cancer cells. That is, to figure out whether ‘normal’ cells that share mutations with cancer cells really are likely to become cancerous or not.”
Dr Iain Frame, Director of Research at Prostate Cancer UK concluded: “This research really goes to show just how complicated prostate cancer is, and highlights why it’s so important for the prostate cancer community to pull together to take results like this forward. That’s the only way to make sure that men at high risk of prostate cancer get the best treatments possible, as quickly as possible.
“We believe these results may have implications for focal therapy, but men who have already had, or are considering, this type of treatment should by no means panic. There’s still more work to do before we can say for sure what this research means for treatment of localised prostate cancer. In the meantime, men should continue to discuss all treatment options with their doctor.”