The first study is about Hodgkin lymphoma patients, more particularly about the young classical Hodgkin lymphoma patients who stay in remission for a certain number of time. The aim of the study was to provide updated information on the relapse risk and loss in life expectancy of Hodgkin lymphoma patients, given that they stay in remission for, for example, two or three years. This information can be interesting, for example, because it can provide information for patients to start with and it also is interesting for providing the backbone of rational follow-up programmes. So if the relapse risk becomes low at one point it’s not efficient or it costs too much money to keep following those patients for a long amount of time.
To do this study we used data from population-wide registers from Denmark, Sweden and Norway and we ended up with a cohort of 2,582 patients which is quite large. A nice thing about these register studies is that they cover the whole population so quite often these clinical trials that you’ll see reported only include patients who were selected and they often do quite a lot better than what we would expect in the real world. So by using these real world patients of just any patient diagnosed in Denmark, Sweden and Norway we avoid this kind of selection bias.
The first main result that we see is that for these young classical Hodgkin lymphoma patients the initial five year relapse risk is about 13%, however if they survive two years without experiencing a relapse then this actually decreases to 5%. So given that you survive, or stay in remission, for two years post-diagnosis then the relapse risk in the upcoming five years is below 5% which is quite reassuring to patients.
The second thing that you notice is that when you stratify this analysis according to whether or not patients are limited or advanced stage at diagnosis you see that initially advanced stage patients have about double the risk of relapsing in the upcoming five years as limited stage patients. However, for those patients who survive three years and stay in remission for three years the difference is actually basically non-existent anymore, so this is very reassuring for advanced stage patients who stay in remission for three years. So the fact that they were advanced stage at diagnosis has basically no further influence on their relapse risk anymore.
The other results describe the loss of life expectancy, so when you look at how much time our Hodgkin lymphoma patients or days are they expected to lose due to their diagnosis when you compare it to healthy people from the general population then you can see that it’s actually quite limited. So if you follow patients for five years they will be expected to survive about 40 days less than general people, or people from the general population. However, if they survive five years and remain in remission for five years this reduces to about 10 days. In addition, especially for limited stage patients, this becomes negligible given that they survive two years. So given that the limited stage patients survive two years and don’t experience a relapse their loss in life expectancy is essentially zero, so they perform essentially as well as you would expect a healthy person to perform.
What can we do with this information?
One of the main implications is that a lot of these follow-up programmes for relapses are not really based on too much data these days. But given that the relapse risk of patients who remain in remission for two years is very limited it might be very interesting to not follow these patients after these two years and instead focus on late toxicities which are more of a problem. So you could save money by not trying to detect relapses which are very unlikely to happen and instead use that money to focus on late toxicities like cardiovascular disease or second malignancies.