A. Chemin

MAGNETIC RESONANCE IMAGING IN THE TREATMENT PLANNING OF RADIATION THERAPY IN CARCINOMA OF THE CERVIX TREATED WITH THE FOUR-FIELD PELVIC TECHNIQUE

PURPOSE To evaluate magnetic resonance imaging (MRI) in the planning of radiation therapy for patients with carcinoma of the cervix treated with a four-field technique. METHODS AND MATERIALS Between May 1994 and February 1995, 18 patients with carcinoma of the cervix were entered in the study (1 T1 N-; 2 T2a N-; 1 T2b NO; 10 T2b N-; 2 T2b N+; 2 T3b N+). Node status was assessed by a laparoscopic pelvic lymphadenectomy. During the first step, all the patients were simulated with an isocentric four-field pelvic technique. In one group (11 patients) simulation was done based on clinical examination, computed tomography (CT), and standard guidelines. In the second group (seven patients) simulation was based on clinical examination, CT, and with the help of diagnostic MRI, which was available at that time. During the second step, MRI in treatment position with skin markings of the isocenter of the radiation fields was then performed in every patient. During the third step, in each patient, the simulated radiation fields were correlated with the MRI defined target volume by superimposing them on midsagittal and midcoronal MR images. The adequacy of the margins was arbitrarly defined as 1 cm around the MRI defined target volume (tumor of the cervix and its extension, and uterus). RESULTS In the first group (11 patients), MRI in treatment position led to a change in 7 patients: six inadequate margins in the lateral fields and one in the anterior and lateral field. In almost all the cases, the adjustments were of an increase of 10 mm, equally matched between the anterior and posterior borders of the lateral fields. In the second group (seven patients), MRI in treatment position has led to a change in lateral fields in five patients. The mean adjustment was 10 mm: four increases (two anterior border, one posterior border, one anterior and posterior border), and one decrease of the posterior border. In the two groups, modifications of the anterior border of the lateral fields have allowed adequate margins around the uterine fundus and modifications of the posterior border have allowed adequate coverage of the cervical tumor. CONCLUSION When treating carcinoma of the cervix with a four-field radiation technique, standard portals do not exist. The design of lateral fields has to be based on individual morbid anatomy, which is given accurately by diagnostic MRI. Magnetic resonance imaging in treatment position assesses the design of simulated lateral fields.

EVALUATION OF WHOLE ABDOMINAL IRRADIATION IN OVARIAN CARCINOMA WITH A FOUR ORTHOGONAL FIELDS TECHNIQUE

PURPOSE The purpose of this study is to evaluate the toxicity and the results of abdominopelvic irradiation with a four orthogonal fields technique in patients with ovarian carcinoma. METHODS AND MATERIALS Between May 1981 and December 1990, 167 patients with ovarian carcinoma have been treated with whole abdominal irradiation: 62 patients with no or minimal residual disease < 2 cm after initial surgery (group 1) and 105 patients with no residual disease or macroscopic residual disease < 2 cm assessed by second-look surgery after incomplete debulking surgery and cisplatin-based polychemotherapy (group 2). Irradiation was performed by a four orthogonal fields technique. Thirty grays were given with a 25 MV photon beam (1.5 Gy/fraction/day, 20 fractions over 30 days). Boosts were performed in 50 cases (median dose of 15 Gy). RESULTS With a median follow-up of 68 months, the 5-year actuarial survival rate was 50% in the entire group, 67% in group 1, 40% in group 2, and 84% in T1, 61.5% in T2, 38% in T3. Five-year actuarial survival was analyzed according to the residuum: (a) after initial surgery (no residual disease: 70%, residual disease: 36.5%), (b) after second-look surgery: 76% in patients with a negative second look, 66% in patients with microscopic residual disease, 22% in patients with macroscopic residual disease and secondary surgical reduction, and 10% in patients with small unresectable nodules. Nine percent of the patients failed to complete irradiation acute side effects related. Five percent required surgery for bowel obstruction. CONCLUSION The abdominopelvic irradiation with this four orthogonal fields technique was associated with tolerable acute toxicity and a low risk of serious late complications. Similar late results to have been reported whole abdominal irradiation with chemotherapy in patients with negative or microscopic residual disease after surgery. Randomized trials comparing these two adjuvant treatments are warranted.