CHILDHOOD SOLID TUMORS
In the past the major treatment modality to achieve cure in children with malignant solid tumors was complete surgical removal. However, if the lesions were extensive, vascular or physically inaccessible these attempts might be dangerous. Today, surgery forms an important cornerstone of tumor therapy as part of a multimodality treatment approach. For some localized tumors initial or eventual excision may be the critical factor in determining patient survival. However, the most important aspect of surgery in advanced tumors now often involves the timing of the procedure and how it relates to the adjuvant in chemotherapy and/or radiation and contributes to the overall local and systemic therapy program.
The concept of benign biology in some childhood tumors has modified the surgical imperative for radical resection. Long-term survival has been noted in some cancers after complete excision and minimal adjuvant therapy. However, for more widespread disease, carefully planned surgical removal of viable tumor is worthwhile. Preoperative chemotherapy may allow delayed primary excision of tumors, but eventual complete resection at secondary procedures or debulking operations may still be of value in specific circumstances. Appropriate efforts in local tumor control can now be accomplished with a variety of innovative technical options, which can reduce operative morbidity and mortality. Current modalities which have shown some success in various tumors include hyperthermia, intraoperative radiation, ultrasonic aspiration, auto-transfusion and hemodilution, radioimmune guided surgery, laser therapy, microwave coagulation, regional chemoperfusion, and brachytherapy.
Most important advances in childhood solid tumor treatment centered around the efforts of the cooperative study groups. The solid tumor study for metastatic cancer was opened in 1962 and the initial studies for localized lesions were developed for kidney tumors in 1969. These trials were designed to register all patients with malignant solid tumors and surgeons aimed to make the operative procedures as comparable as possible by preparing surgical guidelines to define appropriate procedures. Experienced multidisciplinary steering committees organized these efforts, which were expanded to include childhood sarcomas in 1972, germ cell tumors in 1978 and liver tumors in 1980s. The liver studies were especially important since complete surgical resection even if successful did not cure all of the patients and, issues such as adjuvant chemotherapy, irradiation for resection margins and secondary operations were shown to improve outcomes.
In summary, the impressive improvements in survival for childhood cancer over the past 30 years could only have occurred with cooperative efforts of surgeons, pediatric oncologists and radiation therapists. This was necessary to improve the 20% cure rates for localized solid tumors in the 1940s to the optimal standardized multimodality therapy such that by the year 2000, more than 80% of children with cancer will outlive their malignancy. The understanding of tumor biology in terms of cell growth and regulation has led to the principles of modern chemotherapy using drugs before and after surgery. Further strategies including utilizing active and passive immunity techniques, cancer vaccines and immunotoxins are also employed. In addition to these systemic treatments, the future of local tumor control interventions ranging from traditional surgery to innovative operative techniques is exciting. For example, utilizing computerized based imaging techniques to deliver treatments as in stereotactic radiotherapy will become increasingly important in young patients. Cryosurgery may destroy tumor tissue by the freeze-thaw process while hyperthermia may have a selective lethal effect on malignant cells, which have unique sensitivities to high temperatures. Regional tumor treatment strategies may also include selective catheterization for delivery of chemotherapy and intraoperative imaging techniques with radioimmune guided surgery. The techniques currently available to experienced pediatric surgical oncologists is extensive and should define potentially favorable outcomes in children with malignant solid tumors.
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