We were hearing this morning about ductal carcinoma in situ and the idea of actually scoring the risk of recurrence, doing this with a gene test. What did you make of the study presented by Dr Rakovitch on this, because there were some questions about whether you should even do DCIS excision to begin with, weren’t there?
There’s a big controversy about DCIS. Many people feel that many of them are over-diagnosed and over-treated and yet when we do diagnose one of them we’re obligated to treat them because we know a proportion will go on if not treated to become invasive breast cancers. What we have been unable to do is to identify those that are not going to do that, that are just going to be indolent and never cause a problem. So what’s happening as we begin to subdivide these DCISs into various subtypes, including genomic profiles which is what the DCIS score was all about, we’re beginning to be able to identify those that are very indolent, probably not going to cause a problem in a woman’s life, and those that are more aggressive and with a higher risk of recurrence in the breast and possibly a recurrence as an invasive breast cancer.
And, in a nutshell, what did Dr Rakovitch discover?
She showed, similar to a more prospective study done a year ago, that if you have a low DCIS risk score your risk of having a recurrence in the breast of either invasive or recurrent in situ cancer is much lower than it is if you have an intermediate or high risk score in which case your risk of recurrence in the breast is higher.
Now it’s very difficult for doctors, though, to withhold therapy that might save the life of a patient and I think here we’re talking about withholding radiation therapy. What do you think about the data? Were they strong enough to make a confident decision to help your patient decide not to have radiation therapy?
It provides additional information to help us make that recommendation. After all, in non-invasive breast cancer in women above 65 years of age who have small oestrogen receptor positive tumours and negative lymph nodes, we’re not obligated to give them radiation. In fact, there are several studies now suggesting that they don’t need it; even though the risk of recurrence in the breast is a little bit greater, we can diagnose it relatively early and treat it at that time. So it makes a lot of sense that we ought to be able to do the same thing in ductal carcinoma in situ, which is really hardly even say it’s a cancer in the sense that it hasn’t even spread outside the milk duct, much less to other parts of the body. So, yes, this additional information provides me with more confidence that I can eliminate radiation for certain women.
And you say additional information, how much weight would you give to that compared with classical risk factors?
That’s a tough one. I haven’t digested the data that well yet but I think I would consider it as additional information, maybe equal weight to things like age of the patient, how healthy are they otherwise, what does the tumour look like, what are its characteristics, is it oestrogen receptor positive or negative etc. Then take into account the gene test as well and put that information all together to make a decision.