New Study Looks at Secondary Cancer After Hodgkin's Lymphoma
The researchers followed up 3,905 patients treated in Holland for the disease between 1965 and 2000. They estimated the rates of secondary cancer after the patients had been cured, that is to say once they had remained free of Hodgkin’s lymphoma for five years after treatment. It was expected that, with newer and "gentler" forms of treatment, the incidence of such cancers had fallen.
This, however, was not the case, at least for what are known as solid cancers (the incidence of blood cancers had indeed fallen, but they accounted only for a small proportion of the total). Overall, the patients had a risk of developing secondary cancer four times greater than if they had not had Hodgkin’s lymphoma treated by radio- and chemotherapy, but the rate had not fallen.
However, the difficulty of hitting a moving target was illustrated by the example of cancer of the breast, which accounted for 40 percent of the secondary cancers in women. The incidence had remained the same over the years, but such cancer was detected earlier in cases treated more recently. This was because, more recently, women underwent screening more frequently, and therefore detection rates may have risen. In other words, the meaning of the finding that rates of breast cancer had remained the same was uncertain.
Moreover, treatment of Hodgkin’s lymphoma has changed further since 2000, so that it is impossible to apply the paper to current practice. To find the comparative effects of current practice, we shall have to wait another fifteen years.
The paper makes no mention of death rates among the treated patients: whether they have risen, fallen or remained the same. Survival after secondary cancer may have increased, so that overall survival would have increased. What the paper does make clear, however, is that, as in politics, it is sometimes difficult to disentangle the effects of what we are doing.