RBE variation between fast neutron beams as a function of energy. Intercomparison involving 7 neutrontherapy facilities.

In fast neutron therapy, the relative biological effectiveness (RBE) of a given beam varies to a large extent with the neutron energy spectrum. This spectrum depends primarily on the energy of the incident particles and on the nuclear reaction used for neutron production. However, it also depends on other factors which are specific to the local facility, eg, target, collimation system, etc. Therefore direct radiobiological intercomparisons are justified. The present paper reports the results of an intercomparison performed at seven neutrontherapy centres: Orléans, France (p(34)+Be), Riyadh, Saudi Arabia (p(26)+Be), Ghent, Belgium (d(14.5)+Be), Faure, South Africa (p(66)+Be), Detroit, USA (d(48)+Be), Nice, France (p(65)+Be) and Louvain-la-Neuve, Belgium (p(65)+Be). The selected radiobiological system was intestinal crypt regeneration in mice after single fraction irradiation. The observed RBE values (ref cobalt-60 gamma-rays) were 1.79 +/- 0.10, 1.84 +/- 0.07, 2.24 +/- 0.11, 1.55 +/- 0.04, 1.51 +/- 0.03, 1.50 +/- 0.04 and 1.52 +/- 0.04, respectively. When machine availability permitted, additional factors were studied: two vs one fraction (Ghent, Louvain-la-Neuve), dose rate (Detroit), influence of depth in phantom (Faure, Detroit, Nice, Louvain-la-Neuve). In addition, at Orléans and Ghent, RBEs were also determined for LD50 at 6 days after selective abdominal irradiation and were found to be equal to the RBEs for crypt regeneration. The radiobiological intercomparisons were always combined with direct dosimetric intercomparisons and, when possible in some centres, with microdosimetric investigations.

The Saudi experience with neutron therapy in locally advanced head and neck cancers.

The neutron therapy program at King Faisal Specialist Hospital and Research Center conducted a phase II study to evaluate the toxicity and efficacy of neutrons against conventional external megavoltage irradiation in patients with locally advanced head and neck malignancy. One hundred and nineteen patients were allocated to receive either photons (46/119) or neutrons (73/119). Radiation effects were scored according to the EORTC/RTOG criteria; data was collected weekly during treatment, once a month for the first year and at 6-month intervals subsequently. While acute effects were scored in all patients, only 59 were evaluable for late effects and locoregional control. A composite of the average reaction results were obtained using this information, to compare them in time, for acute and late effects in both arms of the study. The maximum acute reactions in the two groups were similar. In the majority of the patients (80%) acute skin and mucosal reactions occurred during the last week of treatment. The changes in the subcutaneous tissues and salivary glands became clinically apparent at 3 months or later. Salivary gland toxicity was more severe in the photon arm and the difference was statistically significant at 3 months (P = 0.04) but this was lost at 12 months. Late effects for skin and subcutaneous tissues were significantly more severe in the neutron arm with P values of 0.04 and 0.01 respectively. Three patients in the neutron arm died of grade 4 radiation complications. The local control and survival were similar in both groups.

Gastrointestinal lymphoma in adults: clinical features and management of 300 cases.

BACKGROUND/AIMS: Gastrointestinal lymphoma is a rare disease. A study was conducted to assess its prevalence and clinical features in adult patients with lymphoma. METHODS: Retrospective analysis of 1352 patients with adult non-Hodgkin's lymphoma showed 300 (22%) cases with gastrointestinal involvement at initial presentation. RESULTS: Of the 185 patients with primary gastrointestinal lymphoma, 94 (51%) had gastric primary lymphoma and the rest (49%) had a lymphoma of intestinal origin. Patients with intestinal lymphoma were considerably younger (median age, 35.0 years), frequently had multifocal disease (14%), and had a 10-year survival rate of 48%. Cases with gastric primary lymphoma had a median age of 54.5 years (P < 0.001) and rarely had multifocal disease (1%; P < 0.001) but had an equal 10-year survival rate of 53% (P = 0.431). For both groups, the combined surgical resection followed by chemotherapy led to better 10-year survival (45%) compared with either modality used alone (0% and 35%, respectively; P < 0.05). Better survival was also noted in ambulatory patients, younger patients, those with localized disease, and those without intestinal perforation. Another 115 patients had gastrointestinal involvement secondary to disseminated disease with frequent high-grade histology (29%) and a poor 10-year survival rate of 22%. CONCLUSIONS: Gastrointestinal involvement is relatively common in patients with adult lymphoma. Multimodality treatment appeared superior to therapy with either surgery or chemotherapy used alone.

Obtaining pre-radiation therapy dental clearance.

Patients scheduled to receive radiation therapy that involves the mandible, maxilla or salivary glands should be referred for dental consultation, assessment and clearance before therapy begins. A form that aids the radiation oncologist and the dentist in patient referrals is presented.

Neutron therapy in Saudi Arabia: an overview and results of dose searching study in head and neck cancer.

The King Faisal Specialist Hospital and Research Centre is the only center in the Middle East that incorporates a neutron therapy facility. The neutron beam is produced by a cyclotron, which produces a beam by either a (d(15)+Be) or (p(26)+Be) reaction. The beam from the proton reaction is selected for therapy because of its superior physical characteristics. These were verified by an intercomparison conducted by the European Organization for Research on Treatment of Cancer (EORTC) Heavy Particle Therapy Group. Full beam data are presented. The first study in the neutron therapy Program is on the treatment of squamous cancers of the head and neck. This consists of two parts. Part I is a dose searching phase and Part II is a comparison of our current photon treatment versus neutrons using the neutron dose selected by Part I of the study. Results of the dose searching phase (Part I) are presented.

Neutron therapy for locally advanced head and neck squamous cell carcinoma: optimum dose search.

28 patients with locally advanced primary squamous cell carcinoma of the head and neck received neutron therapy and were randomized between two dose levels: 145 cGy n gamma x twelve fractions, three fractions per week (total 17.4 Gy n gamma). 155 cGy n gamma x twelve fractions, three fractions per week (total 18.6 Gy n gamma). Acute toxicity for skin, mucous membrane, salivary and subcutaneous tissues was graded using the EORTC/RTOG scoring system. Analysis indicates 17.4 Gy n gamma as "safe". A further twelve patients are to be assigned to the higher dose (18.6 Gy n gamma) before making a final dose selection.

Relative biological effectiveness (RBE) of p(26) + Be neutrons from the King Faisal Specialist Hospital and Research Centre CS-30 cyclotron measured by testis weight loss.

Testis weight loss of C3H and Swiss-Webster (SW) mice was used as endpoint to determine the relative biological effectiveness (RBE) of p(26) + Be fast neutrons with respect to Co-60 gamma irradiation. Percent weight loss versus dose curves showed two components. Comparing first component effects, the RBE was 3.4 (C3H) and 3.7 (SW); when the second component was used, the RBE was 2.6 and 2.7 (C3H), and 3.5 (SW). When percent weight loss was plotted versus log dose, parallel lines were obtained, giving an RBE of 3.9 and 4.1 (C3H), and 4.2 (SW). Results were compared with published values and RBE as a function of fast neutron energy was plotted. A good correlation was found. Discrepancies seem to be mostly due to the use of different baseline radiation. When a constant correction is made, most of the values fit a single line. The possibility of using this approach as a substitute for international comparisons is discussed.

Nasopharyngeal carcinoma in Saudi Arabia: a retrospective study of 166 cases treated with curative intent.

A retrospective review was performed of the medical records of 166 adult patients with biopsy-proven carcinomas of the nasopharynx treated with curative intent at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. All patients were treated between June 1975 and December 1985 using megavoltage therapy equipment. Most patients presented with advanced nodal disease: 23 patients (13.9%) were N0, 16 patients (9.6%) were N1, 29 patients (17.5%) were N2, and 98 patients (59%) were N3. The overwhelming majority of patients had nonkeratinizing lesions (158/166). At the time of analysis, mean follow-up time was 24.2 months (range 2-108). Actuarial curves are presented for local/regional control as a function of T-stage and N-stage and for survival and time to development of distant metastases as a function of N-stage. At 4 years local/regional control was 70% for T1 lesions, 59% for T2 lesions, 30% for T3 lesions, and 35% for T4 lesions. There was little correlation between local/regional control and N-stage being about 50% at 4 years for all nodal subgroups. Only six patients exhibited an isolated first failure in the regional nodes alone, whereas 60 patients failed initially at the primary site (either alone or in conjunction with a simultaneous nodal failure). The development of distant metastases correlated to some extent with nodal disease ranging from 20% at 4 years for T1/T2 N0 patients to 70% for patients who initially presented with N3 disease. Survival data was more difficult to obtain due to cultural biases in a medically unsophisticated patient population. True survival curves are bounded by calculating actuarial curves in two ways: death as the failure endpoint and death plus lost-with-active-disease as failure endpoints. In terms of the latter curves, at 4 years "survival" ranged from 39% for patients with T1/T2 N0 lesions to 23% for patients with N3 lesions.

Epidemiology and clinical characteristics of testicular tumors in Saudi Arabia: King Faisal Specialist Hospital and Research Centre experience.

The data on 62 patients with germinal testicular tumors seen at King Faisal Specialist Hospital and Research Centre between January 1977 and June 1983 were analyzed to determine the epidemiologic and clinical characteristics of the disease in Saudi Arabia. Fifty-seven patients were Saudis. The geographic distribution of Saudi patients seemed to coincide with population concentrations. Testicular seminomas (TS) and non-seminomatous testicular tumors (NSTT) comprised 50% each. The mean age was 41 and 27.8 years for TS and NSTT, respectively. Fifteen patients had cryptorchidism of the involved testicle. Three patients with NSTT had a history of trauma to the involved testicle. The most common presentations were painless testicular swelling (51.6%), painful swelling (16%), and abdominal or inguinal swelling (21%). The delay between the onset of symptoms and referral (mean 15 months) was considerable. Eighty percent of patients with NSTT and 45% of those with TS had advanced disease at referral.

Kaposi's sarcoma and its management by radiotherapy.

Thirteen patients with Kaposi's sarcoma were treated by radiotherapy between 1975 and 1984. Five patients were kidney transplant recipients receiving immunosuppressive drugs, while eight patients had spontaneous Kaposi's sarcoma. Eleven patients were followed up for periods from two to 63 months (mean, 27 months). All patients had complete response throughout the period of follow-up except one patient who developed recurrence one year after completion of radiotherapy. There was no difference in the response between transplant recipients and patients with spontaneous disease. This response was also unrelated to the dose or type of radiation used. Radiotherapy has been found effective in the local control of Kaposi's sarcoma with complete relief of symptoms and minimal morbidity.

Pattern of cancer in Saudi Arabs referred to King Faisal Specialist Hospital.

A total of 7251 histologically confirmed new cases of cancer (4117 males and 3134 females) were seen in the 6-year period 1979 to 1984 at the King Faisal Specialist Hospital and Research Centre in Riyadh, Saudi Arabia. The crude relative frequencies of cancer at various primary sites have been determined with reference to sex, age, geographic origin, and year of diagnosis. The most common cancer sites among males were non-Hodgkin's lymphomas, esophagus, lung, liver, stomach, and nasopharynx. Breast cancer was the most common tumor among the females, followed by non-Hodgkin's lymphomas and cancers of the thyroid, esophagus, cervix, and ovary. The most marked deviations were found in the Southern Region for cancers of the oral cavity (2.4 times higher), bladder (1.8 times higher), and lung (4.3 times lower). Known etiologic factors, such as local chewing, smoking habits, and schistosomiasis are likely to be responsible for these differences. Upward trends in cancers of lung, breast, colon and rectum, and the downward trend in esophageal cancer may reflect the rapid pace of modernization.

Extrasellar prolactinomas: successful management of 24 patients using bromocriptine.

24 patients with an extrasellar prolactinoma (mean prolactin 4,722 ng/ml), 8 of whom had previously had surgery, received 5-40 mg bromocriptine daily for 13-252 weeks. The mean prolactin level had fallen 89% at 2 days, 95% at 6 weeks, and 15 patients achieved normal values. Tumor shrinkage occurred in all 9 patients rescanned within 2 weeks and later was documented in 23; in 18 the extrasellar tumour disappeared. 12 patients had visual abnormalities; 7, including 2 who had been completely blind, improved within 1 week. 2 patients had normal prolactin levels after withdrawal of bromocriptine, 1 following radiotherapy and the other during two uncomplicated pregnancies. Bromocriptine is safe and effective. We conclude that medical treatment should always precede surgery unless pituitary apoplexy causes sudden deterioration of vision. Most patients will subsequently require radiotherapy or surgery for permanent cure.

Evaluation of fetal dose from megavoltage irradiation of the knee and neonate followup.

A 24-yr-old female patient who was to undergo radiation therapy management for a recurrent low-grade fibrosarcoma on her right knee was found to be 9 weeks pregnant. The patient and her relatives insisted on carrying the pregnancy to maturity, despite undergoing irradiation of her right knee for local control of her disease and to take the teratological risk, if any, that it entails. This paper discusses the measurement of scattered dose in water, fetal dose estimation in an Alderson-Rando human phantom and possible ways of minimizing it.