One major benefit of having practiced medical oncology for over three decades is, increasingly, I meet up with former patients who survived their cancer and its treatment.
A few were teenagers at the time they were under my care. After recovering from the trauma of their surgery, radiation, and chemotherapy, most went on to complete their education, marry and have healthy, normal children. Now in their 40s, they are planning the weddings of their own sons and daughters!
But not all the stories end happily. One young woman survived rigorous treatment, including amputation of her leg, for osteogenic sarcoma (bone cancer) in the 1970s, only to once again become my patient 27 years later. This time, it was breast cancer. Life can be very unfair.
Yet, according to new statistics just published by a group of Canadian and American researchers in the latest issue of the Journal of Clinical Oncology, her story is not all that uncommon.
Summarizing the results of the Childhood Cancer Survivor Study (CCSS), which followed into adulthood almost 20,500 children (infancy to 20) diagnosed with cancer between 1970 and 1986, the authors report that pediatric survivors have a 15-fold increased risk of developing second cancers in adulthood. For breast cancer, the rate is almost 5-fold higher than average.
While some of the increased risks of second malignancies may result from an underlying genetic susceptibility to develop cancer, the CCSS lays much of the blame on the life-saving treatment itself. For example, children who received radiation therapy had 2 to 4 times the risk of developing second cancers. A similar increase was noted for youngsters who received high doses, or certain types, of chemotherapy drugs.
Moreover, the younger the child at the time cancer was diagnosed and treated, the greater the chance of developing another cancer. For example, children diagnosed between infancy and age four had a 2.7-higher rate of developing second cancer five to nine years later.
Unfortunately, second cancers are only part of the story. Survivors of childhood cancer were also found to have an increased chance of dying of heart disease (7-fold greater risk), lung disease (8.8-fold greater risk), and other medical causes (2.6-fold greater risk).
Commenting on these findings, the authors stated: “These elevated rates draw important attention to the fact that therapy essential for cure of primary malignancies may well have long-term consequences many years after the risk of recurrence of the primary tumor has passed. Such knowledge should not only be communicated to patients and their families… during the discussion of of the risks and benefits of therapy, but also should be used to guide current care of long-term survivors by specifically targeting groups at high risk for late mortality.”
Lest the take-home message be too gloomy, I would emphasize that, with the exception of acute leukemia, most childhood cancers were incurable in the 1970s when I was training as an oncologist. Thirty years later, the 5-year survival rate for all pediatric malignancies combined exceeds 80%.
Clearly, we have made tremendous strides in treating cancer in children, but at a significant cost to their health in later life. Now that we understand more clearly the treatment-related causes of delayed mortality, we can begin to develop new, safer, strategies in an effort to save even more young lives far into the future.