Roughly 10% of childhood cancer survivors suffer from repeated resurgences of tumors throughout their adult lives.
The population of childhood cancer survivors is by no means an exclusive club; as more medical discoveries have been made, survival rates have soared. It is estimated that 366,000 Americans living today are childhood cancer survivors, and long-term childhood cancer survival rates (now 80% nationwide) have never been higher. The growing population of childhood cancer survivors merits celebration, but unfortunately, that celebration may have to wait. According to a recent study—the largest of its kind—roughly 10% of childhood cancer survivors suffer from repeated resurgences of tumors throughout their adult lives.
The study was performed by researchers from St. Jude’s Research Hospital, involving 14,358 participants; the study, known as the Childhood Cancer Survivor Study(CCSS), was federally funded and included survivors whose cancers were diagnosed between the years 1970 and 1986, when the participants were twenty years old or younger.
The researchers reported that 1,382 (9.6%) of the survivors participating in the study developed new tumors unrelated to their original cancers; 386 of these survivors (30%) even developed third tumors, while 153 survivors went on to develop four or more tumors.
"These findings show that when you describe adult survivors of childhood cancer it is not sufficient to describe their risk of a first subsequent cancer, but to acknowledge that some of these patients are at risk for multiple cancers,” said Gregory Armstrong, M.D., the study's principal investigator and an assistant member of the St. Jude Department of Epidemiology and Cancer Control. “This is the first study to more fully enumerate that risk."
The CCSS, led primarily by St. Jude scientists, was put into action in the year 1994. The study’s purpose was identifying challenges that childhood cancer survivors might have to face in their adult years, as well as developing new approaches to easing or preventing late effects of treatments.
About 50% of the participants in this study had survived a minimum of twenty-three years since their childhood cancers were discovered; the median age of the participants was thirty-two years old.
Radiation became a chief focus of the study. Nearly 70% of the participants were given radiation as part of their childhood cancer treatment. As such, there seems to be a correlation affirmed through this research connecting radiation therapy with an increased risk of developing additional tumors—malignant and benign—later in life. The researchers found, for instance, that female survivors who received radiation treatment as a part of their childhood cancer treatment were some of the highest risked individuals for developing later tumors, particularly in the breast.
For 735 survivors, the second tumors were malignant and thus life-threatening, but risks were also connected to benign tumors some survivors developed. The researchers found that survivors whose second tumor was a non-melanoma skin cancer had a one in five chance of developing a third and more aggressive cancer within fifteen years; this population of the participants included 485 survivors with either basal or squamous cell skin cancers.
Of the 176 survivors whose second tumors were discovered in the breast, forty-two women developed multiple tumors. The researchers reported that, for the majority of women in these cases, the tumors developed separately in both breasts almost concurrently. "This finding reinforces previous reports of multiple breast cancers and defines them as a significant risk," Armstrong said.
"These survivors are candidates for additional genetic evaluation to look for an underlying genetic propensity for tumor development or an inability to protect healthy cells against the harmful effects of radiation," Armstrong reported.
The researchers stated that these findings show the necessity of screening for all types of cancer in adults who have survived childhood cancer. Female survivors, for example, should begin getting mammograms at the age of twenty-five instead of the recommended age of forty if their childhood cancer treatment included chest radiation of twenty “grays”—a measure of absorbed radiation—or more.
"Too often, survivors still are not getting these important cancer screening tests beginning as early or as often as recommended," Armstrong concluded.
This study is published online in the Journal of Clinical Oncology.