[3-Dimensional irradiation planning in brain tumors. The advantages of the method and the clinical results]

PURPOSE

Radiotherapy became an important component in the treatment of brain gliomas. The aim of this study is to analyse several advantages of the three-dimensional conformal radiation therapy in comparison with a two-dimensional conventional technique and to present the clinical results of 43 patients with brain gliomas treated according to a three-dimensional planning.

PATIENTS AND METHOD

Between January 1994 and December 1995, 43 patients with malignant brain gliomas (WHO III and IV) were treated in our department according to a three-dimensional treatment planning. The patients received a total irradiation dose of 60 Gy, 2 Gy/day, 5 days/week. The rate of survival was analysed in relation with the known prognostical factors: histology, Karnofsky index, age, resection status. In 10 patients a three-dimensional treatment planning was compared with a conventional two-dimensional planning: the volume of the normal brain tissue irradiated to high dose levels (95% isodose) and the normal tissue complication probability (NTCP) for the brain by Kutcher and Lyman were comparatively analysed.

RESULTS

The survival rate for the whole group was 14 months. The histology of the tumor, age, Karnofsky index and resection status were important prognostical factors. The three-dimensional planning allows a 15 to 20% reduction in the volume of normal brain tissue irradiated to high dose levels (95% isodose). The NTCP is significantly lower using the three-dimensional technique (range 0.03% to 13%), in comparison with the two-dimensional conventional technique (range 0.1% to 26%). The value of NTCP increases with tumor volume.

CONCLUSIONS

Concerning the tumor control and survival rate, the three-dimensional treatment planning shows no advantages compared to the standard conventional methods. The main advantage of the three-dimensional treatment planning is the possibility to spare normal brain tissue. The possibility to integrate mathematical models in the evaluation of the therapy could give this technique new dimensions.

Fluorine-18-FDG PET and iodine-123-IMT SPECT in the evaluation of brain tumors

The high glucose utilization of normal gray matter limits the detection of brain tumor tissue by PET using 18F-fluorodeoxyglucose (FDG). The aim of this study was to evaluate whether the examination of amino acid transport with the SPECT tracer 123l-alpha-methyl-L-tyrosine (IMT) allows better identification of tumor tissue than FDG-PET.

METHODS

Nineteen patients (16 with gliomas, 3 with nontumorous lesions) were included in the study. Two independent observers classified PET and SPECT images as positive or negative for tumor tissue and defined the extent of tumor with regions of interest. Tracer uptake of FDG and IMT was quantified by calculating the tumor uptake relative to contralateral gray and white matter.

RESULTS

SPECT studies were interpreted concordantly in 18 patients (kappa = 0.77) and all tumors were identified by both observers. PET studies were interpreted discordantly in 4 patients (kappa = 0.52) and only 10 tumors were identified by both observers, interobserver variability in definition of tumor extent was significantly lower in the IMT-SPECT than in the FDG-PET studies (p = 0.03). Mean tumor uptake relative to gray and white matter was 1.93 +/- 0.42 and 2.25 +/- 0.46 for IMT and 0.93 +/- 0.32 and 1.61 +/- 0.52 for FDG. All tumor uptake ratios were significantly (p < 0.01) higher for IMT than FDG, even when only glioblastomas were analyzed. No significant correlation was observed between the various uptake ratios of FDG and IMT.

CONCLUSION

Despite the lower resolution and lower sensitivity of SPECT compared with PET, IMT-SPECT was clearly superior to FDG-PET in the detection and delineation of tumor tissue.

Iridium 192 high-dose-rate brachytherapy--a useful alternative therapy for localized prostate cancer?

We report on a novel protocol involving iridium 192 high-dose-rate brachytherapy and follow-up of up to 130 months in patients with prostatic carcinoma. Using regional anesthesia, five to seven hollow needles are placed within the prostate by perineal puncture under ultrasound guidance. A 9-Gy prostate dose is applied followed by 30 min of hyperthermia (since 1991). This treatment is repeated once after 7 days; 2 weeks later, 18 x 2-Gy external beam radiation (small-field prostate) is added as percutaneous dose saturation. Since 1984 we have treated 40 patients with this protocol. Local tumor control was achieved by means of prostatic biopsy at 18 months after therapy and determination of prostate-specific antigen (PSA) values in about 70% of the patients; after a mean follow-up period of more than 6 years (16-130 months), 80% of the patients show either no evidence of disease or stable disease. We therefore conclude that iridium 192 high-dose-rate brachytherapy is a useful alternative in the treatment of localized prostate cancer in patients who are not eligible for radical prostatectomy.

Oxygen tensions in rodent tumors after irradiation with neutrons

We started investigations on intratumoral oxygen tension after irradiations with reactor fission neutrons using the Eppendorf-pO2 Histograph. Isotransplanted AT17-mammary carcinomas on C3H-mice and osteosarcomas OTS-64 on balb C-mice received 2 or 6 Gy neutrons single dose. Before and at certain points of time after treatment the pO2 values were evaluated. Some tumors with initially low median pO2 values showed a short-lasting increase between 2 and 24 h after irradiation. In those tumors with relatively high pretherapeutic pO2 values the pO2 decreased to the range of hypoxia. A third group of tumors showed no marked changes after irradiation. No tumor stopped growth during the observation period.

[Ultrasound volumetry of cervical lymph nodes during radiotherapy as a method of therapy monitoring]

PURPOSE

Volumetric changes of cervical lymph nodes during radiotherapy (RT) should be evaluated with B-mode sonography. It was our intention to test whether ultrasound could be used for therapeutic monitoring.

METHOD

30 lymph nodes of 20 patients were measured. All patients underwent radiotherapy of the cervical region. All lymph nodes were checked at first one day before RT, and then once a week.

RESULTS

Concerning the volume change, examined lymph nodes showed great differences. Pretreatment volume ranged from 0.26 to 96.5 cm3, median 4.9. Time volume 50%, i.e. time until volume had decreased by 50%, was reached after 21 (+/-11) days. Mean volume reduction was 1.3 (+/-1.6)% each day. Big lymph nodes needed more time until time volume 50%. Time volume 50% itself correlated positively with the therapeutic outcome. Sonographic lymph node volumetry was useful in 85% of all the patients.

CONCLUSIONS

Sonographic lymph node volumetry is a simple and practical method. It can be used easily in clinical routine. Radiotherapist can often gain therapeutically relevant information. We describe the use of sonography for therapy monitoring during RT. This has so far been an unknown potential of the method. However, further evaluation is required.

Locally advanced rectal cancer: resection and intraoperative radiotherapy using the flab method combined with preoperative or postoperative radiochemotherapy

PURPOSE

Surgery often fails to achieve local control in advanced rectal cancer. Additional measures are necessary to prevent local recurrence. The aim of this study was to evaluate intraoperative radiation therapy (IORT) (flab technique) combined with preoperative or postoperative radiochemotherapy.

PATIENTS/METHODS

IORT is performed using a flexible flab containing hollow plastic tubes that are connected to a multichannel afterloading device with a 370 Gbq-192-Ir source. Patients receive an intraoperative dose of 15 Gy. Target volumes were measured in a cadaver experiment. From 1989 to 1993, 38 patients were included in this study. Nineteen patients were staged as T3 tumors by preoperative endosonography (Group I) and 19 as T4 tumors (Group II). Patients in Group I underwent resection (abdominoperineal resection (APR), 16; anterior resection, 3) and IORT, followed by postoperative radiochemotherapy (50 Gy/5-fluorouracil), whereas patients in Group II received preoperative radiochemotherapy (40 Gy/5-fluorouracil) followed by resection (APR, 18; anterior resection, 1) and IORT. Mean follow-up was 25.5 months.

RESULTS

Operative radicality in Group I was RO (13), R1 (3), and R2 (3), and in Group II it was RO (14), R1 (3), R2 (2). R2 resections were attributable to preoperative undetected distant metastases. Perioperative mortality was 0 percent in Group I and 10.5 percent (n = 2) in Group II. Postoperative morbidity was 53 percent (n = 10) in Group I and 84 percent (n = 16) in Group II with delayed sacral wound healing being the predominant problem. Stenosis of the ureter occurred in two patients (Group II). Late or persistent therapy-related complications were seen in two patients in Group I and in six patients in Group II. Local recurrence developed in three patients in Group I (15.8 percent) and in two patients in Group II (10.5 percent). Survival data do not reach statistical significance between the two groups because of small numbers but show a favorable trend for the preoperative radiochemotherapy group. When compared with a matched historical control group of patients receiving resection only, adjuvant/neoadjuvant radiotherapy with resection/IORT improves survival significantly.

CONCLUSION

The flab method is a simple but especially practical technique for IORT in the pelvis. Adjuvant/neoadjuvant therapy combined with resection/IORT is associated with high morbidity but acceptable mortality. Preliminary survival data are encouraging and call for a controlled prospective randomized trial.

[Abdominal irradiation in seminomas: improvement in its planning with MRT]

BACKGROUND

Standard therapy for early stages of seminomas is the irradiation of the para-aortal and paracaval lymphatic vessels.

PATIENTS AND METHOD

Prior to radiotherapy coronal T1-weighted MRI of the abdomen was performed including imaging of target volume and critical organs. The position and course of the large abdominal vessels are projected on simulator radiographs of the abdomen. The target volume is enclosed by blocks, which are individual formed with a 2 cm margin along the vessels.

RESULTS

An irregular course of the vessels in 34% of the patients resulted in modifications of the radiation field compared with standard fields. Thus more than 10% of the volume of the left kidney could be taken out of field in 25% of the patients. Simultaneously fields were enlarged on contralateral side to make sure that the paracaval lymphatic drainage was enclosed.

CONCLUSIONS

MRI-assisted planning of radiotherapy allows a more individualized treatment by visualization of the big abdominal vessels guiding the para-aortal lymphatics. The target volume is surely enclosed, healthy organs are optimal spared.

Combined preoperative chemotherapy and radiotherapy in patients with locally advanced esophageal cancer. Interim analysis of a phase II trial

PURPOSE

The prognosis of patients with locally advanced esophageal cancer (LAEC) remains poor when treated with local modalities. An intensive preoperative program with chemoradiotherapy was used to evaluate the curative resection rate, pathologic response, and survival of patients with LAEC.

PATIENTS AND METHODS

Ninety patients with LAEC were treated preoperatively with chemotherapy (three courses of fluorouracil, leucovorin, etoposide, and cisplatin [FLEP]) followed by concurrent chemoradiotherapy (one course of cisplatin plus etoposide in combination with 40 Gy of radiation). Transthoracic esophagectomy was performed 4 weeks after the end of radiation.

RESULTS

Seventy-two patients were included in this evaluation. Forty-four (61%) underwent a complete tumor resection, and 16 (22%) had no tumor in the resected specimen (pathologic complete response [PCR]). The operative mortality rate was 15%. At a median follow-up time of 22 months (range, 12 to 41), the median survival duration of all 72 patients was 17 months (range, 1 to 41+). The calculated survival rates at 3 years were 33%, 42%, and 68% for all patients, patients after complete resection, and patients with PCR, respectively.

CONCLUSION

This combined treatment modality is active in LAEC, with a PCR in 33% of the patients undergoing surgery. The results appear improved compared with those reported with surgery alone, by approximately doubling the 3-year survival rate. The high efficacy of preoperative chemoradiation warrants evaluation of the role of surgery in LAEC.

[Tissue oxygen partial pressure in human head-neck carcinomas during primary radio-chemotherapy]

BACKGROUND

Experimental data have shown that hypoxic areas in tumors can increase their malignant potential and reduce their sensitivity to chemotherapy and radiation treatment. Until now, the only incomplete data on the oxygenation of human tumors during therapy have been available.

METHODS

The distribution of partial pressure of oxygen in malignant head and neck processes was measured in four patients with lymph-node metastases by means of invasive computerized histography (system manufactured by Eppendorf). All patients received primary radiation treatment and chemotherapy with a two-week respite after 30 Gy and the first cycle of chemotherapy. The total dose consisted of 70 Gy in the tumor and two cycles of chemotherapy. Oxygen measurements were taken before the onset of treatment, before and after the respite, and after completion of treatment.

RESULTS

In three of the four patients, we measured prominent hypoxic areas in the cancers with PO2 values less than 5 mmHg. The average value was between 12 and 46 mmHg. We were impressed by the observation that oxygenation appeared to improve in every cancer during the respite. Only the patient who showed good initial oxygenation without any measurable hypoxic fraction suffered a complete recurrence six weeks after the completion of therapy.

CONCLUSIONS

Prominent areas of hypoxic tissue are present in human head and neck cancers. Radiation treatment and chemotherapy can alter the oxygenation. Further studies are required to investigate the significance of the oxygenation of human head and neck cancers and the changes occurring in it during different types of therapy in order to assess its clinical impact.

Oxygen tension in mouse mammary carcinomas and osteosarcomas after irradiation with reactor fission neutrons

Investigations were made on intratumoral oxygen tension after irradiations with reactor fission neutrons using the Eppendorf-pO2-Histograph. Isotransplanted AT17-mammary carcinomas on C3H-mice and osteosarcomas OTS-64 on Balb c-mice received 2 or 6 Gy neutrons single dose. Before and at certain points of time after treatment the pO2-values were evaluated. Some tumors with initially low median pO2-values showed a short-lasting increase between 2 and 24 hours after irradiation. In the tumors with relatively high median pO2-values before irradiation the pO2 decreased to hypoxic range. A third group of tumors showed no significant changes after irradiation. None of the tumors stopped growth during the observation period.

Hyperthermia--its actual role in radiation oncology. Part IV: Thermo-radiotherapy for malignant brain tumors

BACKGROUND

High-grade malignant gliomas have a dismal prognosis. Only achievement of long-term local control improves overall survival. Conventional treatments have not been successful, but thermoradiotherapy appears to be a promising new approach to this disease.

PATIENTS AND METHODS

The review addresses the various HT techniques applied for brain heating, the biological rationale and experimental studies supporting the use of heat in addition to radiotherapy for brain tumors. Normal brain damage exposed to heat is critically evaluated. Clinical trials implementing HT for tumors of the brain accumulating more than 400 patients are discussed.

RESULTS

HT is a feasible and effective approach to brain tumors. Important selection criteria are tumor size (< 6 cm) and location (supratentorial, peripheral). Acute treatment toxicity is relatively low and long-term side effects are similar to those observed for RT alone. In some studies a high response rate and improvement of survival was achieved. Tumor control and survival depend on histology (anaplastic astrocytoma vs. glioblastoma multiforme), extent of surgery (complete vs. incomplete), tumor status (primary vs. recurrent), age and performance status. Satisfactory heating also correlates significantly with favourable treatment outcome.

CONCLUSIONS

The encouraging results of clinical trials may be biased by favourable tumor and patient selection. Randomized clinical trials comparing RT alone versus combined RT-HT for advanced and recurrent brain tumors are justified. Part I has covered biological and technical fundamentals of clinical hyperthermia and has been published in Strahlenther. Onkol. 168 (1992), 183-190. Part II has covered clinical fundamentals and results in superficial tumors of clinical hyperthermia and has been published in Strahlenther. Onkol. 169 (1993), 633-654. Part III has covered clinical rationale and results in deep seated tumors and has been published in Strahlenther. Onkol. 171 (1995), 251-264.

Hyperthermia--its actual role in radiation oncology. Part III: Clinical rationale and results in deep seated tumors

PURPOSE

Combined hyperthermia and radiation therapy has been reported to yield higher complete and durable responses than radiotherapy alone in superficial tumors. In deep seated tumors the effect of the combined treatment is still under research.

METHODS

The literature and own clinical data are reviewed with regard to biological and physical fundamentals and clinical results.

RESULTS

Clinical phase I to II studies have applied regional hyperthermia in the abdomen, the pelvic region and the extremities. Usually primary advanced, persistent or local recurrent and metastatic tumors were selected for treatment either due to poor response to conventional therapy or for effective palliation. The clinical data are presented concerning the following topics: invasive thermometry, temperature parameter in tumor and normal tissue, toxicity, tumor response, treatment planning, clinical trials and prognostic factors. Clinical results of thermoradiotherapy for advanced or recurrent rectal cancer, cervical cancer and soft tissue sarcomas are reviewed in detail. In addition, the prognostic relevance of temperature parameters and physiological conditions such as global tumor perfusion are discussed.

CONCLUSION

Clinical issues of optimization of regional thermoradiotherapy are: improvement of hyperthermia technique, analysis of biological effects and mechanisms involved in temperature elevation, selection of appropriate study concepts for specific tumor sites. Part I has covered biological and technical fundamentals of clinical hyperthermia and has been published in Strahlenther. Onkol. 168 (1992), 183-190. Part II has covered clinical fundamentals and results in superficial tumors of clinical hyperthermia and has been published in Strahlenther.