Irradiation therapy

The proteolytic enzymes, trypsin, chymotrypsin, and chymoral [8076-22-0] in combination, have been used for the treatment of post-operative hand trauma, athletic injuries, and sciatica (214—216). Trypsin has also been used successfully in treating hyaline membrane disease of newborn babies, a condition usually fatal without treatment (217). Immobilized preparations of trypsin are useful in treating acute radiation cystitis following pelvic x-irradiation therapy (218). 

Robinow JS, Shaw EG, Eagan RT, etal. Results of combination chemotherapy and thoracic irradiation therapy for unresectable non-small cell carcinoma of the lung. Int J Radiat Oncol Biol Phys 1989 17 1203-1210. 

Although we are concerned here with chemotherapy only, it is worth noting that irradiation therapy also has a chem-ieal mode of action (Figure 13.2) Energy-rich particles (photons in X- and y-irradiation, electrons or neutrons in partiele irradiation) dispose of their energy in multiple sue-eessive events, giving rise to multiple radicals (mostly derived from water) along their path. These, in turn, may di-... 

Figure 13.2. Mode of action of irradiation therapy. Energy-rich particles cleave water into radicals, which either directly or after combining with oxygen react with DNA to give rise to mutations.

Because of the increased sensitivity of tumors to X-irradiation therapy in the presence of increased tumor oxygen tension, and because nitrogen mustard has an effect on tumors similar to that of ionizing radiation, some investigators have postulated that the tumoricidal effect of csrtotoxic drugs... 

These include mainly thermal ablative techniques such as laser-induced thermotherapy, radiofrequency and microwave ablation, but also chemoembolization as well as selective internal irradiation therapy. 

The development of so-called photodynamic therapy uses lasers for treatment of cancer. The patient is injected with a substance called hematoporphyrin derivative [68335-15-9] which is preferentially localized in cancerous tissues. The patient is later irradiated with laser light, often with a dye laser at a wavelength around 630 nm. The light energy catalyticaHy photooxidizes the hematoporphyrin derivative, releasing materials which kill the nearby cancerous tissue. Normal tissue which did not retain the chemical is not harmed. Photodynamic therapy offers promise as a new form of cancer treatment. 

It has been estimated that using available neutron intensities such as 10 neutrons/(cm -s) concentrations of B from 10—30 lg/g of tumor with a tumor cell to normal cell selectivity of at least five are necessary for BNCT to be practical. Hence the challenge of BNCT ties in the development of practical means for the selective deUvery of approximately 10 B atoms to each tumor cell for effective therapy using short neutron irradiation times. Derivatives of B-enriched /oj o-borane anions and carboranes appear to be especially suitable for BNCT because of their high concentration of B and favorable hydrolytic stabiUties under physiological conditions. 

Male infertility may result from cancer surgery, radiotherapy, hormonal imbalances, or damage of germinal stem cells. Testicular damage from radiotherapy depends on the treatment field, total dose, and fractionation schedule. Depending on the radiation, sperm counts may return to pretreatment levels in 10 to 24 months after therapy or maybe permanent in 80% of men after total-body irradiation for transplant. 

Hormonal therapies that have been studied in the treatment of primary or early breast cancer include antiestrogens, oophorectomy, ovarian irradiation, luteinizing hormone-releasing hormone (LHRH) agonists, and aromatase inhibitors. 

Patients presenting with stage I/II disease generally are curable with subtotal lymphoid irradiation, which involves treatment of the mantle and paraaortic fields. This therapeutic modality has yielded an overall 90% cure rate, with over a decade of follow-up. However, up to one-third of patients will relapse at the site of original disease presentation. If a patient relapses, then it likely will occur in the first 3 years after therapy has been completed. Fortunately, most of these patients are still curable with salvage chemotherapy. 

The prevalence of CNS disease at diagnosis of AML ranges from 5% to 30% in various treatment series. Features associated with the risk of CNS leukemia include hyperleukocytosis, monocytic or myelomonocytic leukemia (FAB M4 or M5), and young age. In most cases, intrathecal cytarabine with or without methotrexate and systemic high-dose cytarabine provide adequate CNS prophylaxis.3 Results from studies have shown that patients with CNS disease at diagnosis can be cured with intrathecal therapy alone without the use of cranial irradiation.11... 

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