Conceptus dose from involved-field radiotherapy for Hodgkin's lymphoma on a linear accelerator equipped with MLCs.

PURPOSE: To estimate the scattered dose to conceptus from involved-field radiotherapy for Hodgkin's lymphoma on a linear accelerator equipped with multileaf collimators. MATERIAL AND METHODS: Anthropomorphic phantoms were used to simulate an average pregnant woman at the 1st, 2nd and 3rd trimesters of gestation. Conceptus dose was measured using thermoluminescent dosimeters. Phantom measurements were performed for the minimum, medium and maximum field dimensions that may be employed during radiation therapy to lymph nodes in the neck, axilla, mediastinum and neck-mediastinum. The components of the scattered dose to conceptus were determined. Phantom exposures were generated with a 6-MV photon beam. RESULTS: Neck irradiation with a tumor dose of 35 Gy resulted in a conceptus dose of 1.1-8.7 cGy depending upon the stage of pregnancy, the distance from treatment volume, and the field size applied. The corresponding conceptus dose ranges from radiotherapy in the regions of axilla, mediastinum and neck-mediastinum was 1.2-14.3 cGy, 3.7-57.7 cGy, and 5.1-91.8 cGy, respectively. The contribution of collimator scatter and head leakage to the total conceptus dose varied from 21% to 80% depending upon the irradiation site and gestational age. CONCLUSION: The conceptus dose associated with cervical node irradiation is below the threshold value of 10 cGy during the entire pregnancy. Radiation therapy to lymph nodes in the axilla, mediastinum and neck-mediastinum may possibly lead to a conceptus dose of > 10 cGy and, therefore, informed decisions about the pregnancy termination should be made.

A case of herpes simplex-associated encephalitis after brain irradiation for lung cancer metastases.

BACKGROUND: Encephalitis caused by Herpes Simplex Virus-1 is a devastating disease with high mortality and disability rates despite adequate treatment. No clear risk factors have been identified although iatrogenic immunosuppression has been suggested, among others. CASE REPORT: A 59-year-old male smoker was diagnosed with metastatic lung adenocarcinoma and was treated with brain and spinal irradiation. Ten days after the completion of radiotherapy and before initiating platinum-based front-line chemotherapy, he developed low grade fever and personality change. Over the next few days, high fever and refractory seizures developed and the patient was diagnosed with Herpes simplex-associated encephalitis after detection of viral DNA in the cerebrospinal fluid via polymerase chain reaction. Despite treatment with acyclovir, the patient remained comatose and died three months after the initial presentation. CONCLUSION: This case illustrates a possible association between brain irradiation and increased risk for Herpes simplex-associated encephalitis. However, the underlying mechanisms have not been elucidated.

Thyroid exposure to scattered radiation and associated second cancer risk from paediatric radiotherapy for extracranial tumours.

This study was conducted to estimate the scattered thyroid dose and relevant second cancer risk from radiotherapy for extracranial tumours during childhood.  Anteroposeterior and posteronaterior field irradiations employed during the treatment of Hodgkin's disease, neuroblastoma and Wilms' tumour were simulated on two humanoid phantoms representing 5- and 10-y-old patients. Measurements were performed using thermoluminescent dosemeters. Practical thyroid lead shields with thicknesses of 2-10 mm were placed in the phantoms' neck region. The lifetime risk for cancer induction was assessed using sex- and age-specific risk factors. Thyroid dose per monitor unit varied from 28.1 to 492.4 µGy by the primary irradiation site and patient's age. The 10-mm-thick lead shield led to a dose reduction up to 28.9 %. For typical prescribed tumour doses, the total risks for thyroid cancer development after radiotherapy of 5- and 10-y-old male patients were 0.05-0.99  and 0.03-0.48 %, respectively. The corresponding risks for females increased to 0.29-5.51 and 0.17-2.94 %.

Phase I/II trial of external irradiation plus medium-dose brachytherapy given concurrently to liposomal doxorubicin and cisplatin for advanced uterine cervix carcinoma.

BACKGROUND AND PURPOSE: Although the standard of care for patients with locally advanced uterine cervix carcinoma is cisplatin-(CDDP-)based chemotherapy and irradiation (RT), the optimal regimen remains to be elucidated. A phase I/II study was conducted to evaluate the dose limiting toxicity (DLT) and the maximum tolerated dose (MTD) of liposomal doxorubicin (Caelyx) combined with CDDP and RT for cervical cancer. PATIENTS AND METHODS: 24 patients with stage IIB-IVA were enrolled (Table 1). They all received external RT (up to 50.4 Gy) and two medium-dose rate (MDR) brachytherapy implants (20 Gy each at point A). The Caelyx starting dose of 7 mg/m2/week was increased in 5-mg/m2 increments to two levels. The standard dose of CDDP was 20-25 mg/m2/week. RESULTS: Concurrent chemoradiation (CCRT) sequelae and the DLTs (grade 3 myelotoxicity and grade 3 proctitis in five patients treated at the 17 mg/m2/week Caelyx dose level) are shown in Tables 2, 3, 4, and 5. After a median follow-up time of 17.2 months (range 4-36 months), four patients had died, 15 showed no evidence of progressive disease, and five (20.8%, 95% confidence interval [CI]: 12.5-29.1%) were alive with relapse (Figure 1). There were seven complete (29.1%, 95% CI: 19.8-38.4%) and 17 partial clinical responses (95% CI: 61.1-80.1%). The median progression-free survival was 10.4 months. Causes of death were local regional failure with or without paraaortic node relapse combined with distant metastases (Table 6). CONCLUSION: The MTD of Caelyx given concurrently with CDDP and RT was determined at the 12 mg/m2/week dose level. The above CCRT schema is a well-tolerated regimen, easy to administer in ambulatory patients, and results appear promising.