Ensuring Happy, Productive Lives for Childhood Cancer Survivors
Overall childhood cancer survival rates now approach 80%. That is an exciting statistic! In childhood acute lymphoblastic leukemia (ALL), cure rates are as high as 95% in some patient groups. When you think back to the mid 60′s, when ALL cure rates were only 5% – that is a phenomenal improvement. And why??? The multi-institutional collaborations of childhood cancer institutions around the world have been able to enroll and treat thousands of patients. With such tremendous numbers of patients, we as pediatric oncologists can ask and answer countless therapeutic questions using randomized trials. Randomized trials test several alternative arms of treatment against each other in an effort to determine if one is better than another. Is Drug A better than Drug B? Is Drug B better given daily than once weekly? Does increasing or decreasing the dose of Drug C have any affect on outcome???The Children’s Oncology Group is a collaborative effort of over 200 institutions whose mission is to continue to improve cure rates but also to focus on avoiding late side effects of cancer therapy. As our cure rates continue to improve it is essential that we embrace the importance of avoiding those potentially life altering delayed, or late, effects of the cancer and the cancer therapy.
One of the first late effects recognized was heart failure in pregnant osteosarcoma (bone tumor) survivors. The anthracyclines (doxorubicin, daunorubicin and idarubicin to name a few) are now well known for their potential for causing late cardiac failure. The risk is related to the cumulative dose a patient is exposed to over time. Pregnant women have an increase in their plasma volume and as that volume in their body increases, it places an extra strain on the heart…thus, the presentation with cardiac failure. We now know to limit the overall exposure to this category of drugs, to monitor heart function closely while on treatment and in follow up. As a result, the incidence of late cardiac failure in all survivors has been reduced.
Nearly all organs are at some risk from cancer therapies those though risks are dependent on the drug delivered, and in many cases, the cumulative dose and exposure to radiation therapy as well. The liver and kidneys are at risk in patients who receive high doses of methotrexate. Fortunately, lasting effects on these organs is rare. Cisplatin, also known as cisplatinum, as well as its sister drug carboplatin, are well known renal toxins and require very close monitoring when patients receive them to avoid acute renal damage. Late pulmonary toxicity is unusual and when seen, is typically due to exposure to high doses of bleomycin, a drug commonly used to treat Hodgkin’s disease in combination with radiation therapy. Those at risk may occasionally develop scarring of the lungs known as pulmonary fibrosis.
At the time of diagnosis, the parents of a child are always most concerned about chance for cure. But beyond that, they want to know if their child will be “normal.” Will they look like everyone else? Will they be able to function in society? Will they be able to have children? Thankfully, most treatments delivered today do not affect growth, fertility or neurological function. Radiation therapy to the brain or spine can cause growth delays and those children routinely end up receiving growth hormone therapy to improve their chances to reach a normal height. Brain tumor survivors who receive very high doses of radiation therapy are at greatest risk not only for multiple hormonal disturbances but also serious learning disorders. Leukemia survivors who receive repeated dose of chemotherapy injected into the spinal fluid which bathes the brain are also at risk for learning disorders though typically much less serious than those brain tumor survivors may develop. Certain categories of drugs, especially the alkylators such as cytoxan, may impact fertility if delivered at very high doses. Pelvic irradiation can also play a role in later infertility. Thankfully, these very serious late effects are rare and therapies today are designed to avoid them.
Perhaps the most disturbing late effect of all is the development of a second malignant neoplasm (SMN), a secondary cancer. Fortunately, these are extremely rare. Risks for the development of secondary cancers include exposure to radiation therapy, high doses of certain drugs such as alkylators and the type of primary cancer. For example, Hodgkin’s disease and retinoblastoma survivors have an especially risk of developing a SMN.
Thankfully, serious late effects are becoming less and less common as our understanding of them continues to grow. Several pediatric oncology programs around the country have developed long-term survivor programs of which the program at Texas Children’s Cancer Center is one of the largest. At the Cancer Center, childhood cancer survivors are seen annually regardless of their current age for detailed physical exams and dependent on their prior therapy, organ system surveillance studies. In addition to the survivor program, Texas Children’s Cancer Center and Baylor College of Medicine worked with others to develop an internet based tool for survivor care. The Passport for Care (PFC) incorporates an individualized treatment summary which is linked to a comprehensive set of survivor care guidelines which can enable any physician to easily determine the appropriate surveillance studies needed for a survivor regardless of where they live. In addition, the PFC serves as an educational tool for survivors, can assist them in finding research studies they may be interested in participating in, link them to local support groups and keep them updated on new findings in survivorship.
Our goal today as pediatric oncologists is to cure as many children as possible without leaving them with life altering late effects of their prior therapy. Our goal is to not only cure…but to ensure our survivors a life time that is happy and productive. Being cured is wonderful…succeeding in life makes it even better!
The information found here is not intended to provide nor should it be interpreted to provide professional medical, legal or financial advice. You should consult a trained professional for more information.
Category: Experts Speak
Tags: Childhood Cancer Survivors, Children’s Oncology Group, growth hormone therapy, Hodgkin’s disease, osteosarcoma, Passport for Care, pediatric oncologists, radiation therapy, second malignant neoplasm, Texas Children’s Cancer Center