RTOG Phase I study on fast neutron teletherapy for squamous cell carcinoma of the esophagus

Dosimetric rationale and preliminary experience in proton plus carbon-ion radiotherapy for esophageal carcinoma: a retrospective analysis

BACKGROUND

Concurrent chemoradiotherapy has been standard of care for unresectable esophageal carcinoma. There were no reports on proton radiotherapy (PRT) plus carbon-ion radiotherapy (CIRT) with pencil beam scanning (PBS) for esophageal carcinoma. This study evaluated the tolerability and efficiency of proton and sequential carbon-ion boost radiotherapy for esophageal carcinoma.

METHODS

From April 2017 to July 2020, 20 patients with primary esophageal carcinoma at stages II-IV were treated with PRT plus sequential CIRT with PBS. A median relative biological effectiveness-weighted PRT dose of 50 Gy in 25 fractions, and a sequential CIRT dose of 21 Gy in 7 fractions were delivered. Respiratory motion management was used if the tumor moved > 5 mm during the breathing cycle. A dosimetric comparison of photon intensity-modulated radiotherapy (IMRT), PRT, and CIRT was performed. The median times and rates of survivals were estimated using the Kaplan-Meier method. Comparison of the dose-volume parameters of the organs at risk employed the Wilcoxon matched-pairs test.

RESULTS

Twenty patients (15 men and 5 women, median age 70 years) were included in the analysis. With a median follow-up period of 25.0 months, the 2-year overall survival and progression-free survival rates were 69.2% and 57.4%, respectively. The patients tolerated radiotherapy and chemotherapy well. Grades 1, 2, 3, and 4 acute hematological toxicities were detected in 25%, 30%, 10%, and 30% of patients, respectively. Grades 3-5 acute non-hematological toxicities were not observed. Late toxicity events included grades 1, 2, and 3 in 50%, 20%, and 10% (pulmonary and esophageal toxicity in each) of patients. Grades 4-5 late toxicities were not noted. PRT or CIRT produced lower doses to organs at risk than did photon IMRT, especially the maximum dose delivered to the spinal cord and the mean doses delivered to the lungs and heart.

CONCLUSIONS

PRT plus CIRT with PBS appears to be a safe and effective treatment for esophageal carcinoma. PRT and CIRT delivered lower doses to organs at risk than did photon IMRT. Further investigation is warranted.

Particle beam therapy (hadrontherapy): basis for interest and clinical experience

The particle or hadron beams deployed in radiotherapy (protons, neutrons and helium, carbon, oxygen and neon ions) have physical and radiobiological characteristics which differ from those of conventional radiotherapy beams (photons) and which offer a number of theoretical advantages over conventional radiotherapy. After briefly describing the properties of hadron beams in comparison to photons, this review discusses the indications for hadrontherapy and analyses accumulated experience on the use of this modality to treat mainly neoplastic lesions, as published by the relatively few hadrontherapy centres operating around the world. The analysis indicates that for selected patients and tumours (particularly uveal melanomas and base of skull/spinal chordomas and chondrosarcomas), hadrontherapy produces greater disease-free survival. The advantages of hadrontherapy are most promisingly realised when used in conjunction with modern patient positioning, radiation delivery and focusing techniques (e.g. on-line imaging, three-dimensional conformal radiotherapy) developed to improve the efficacy of photon therapy. Although the construction and running costs of hadrontherapy units are considerably greater than those of conventional facilities, a comprehensive analysis that considers all the costs, particularly those resulting from the failure of less effective conventional radiotherapy, might indicate that hadrontherapy could be cost effective. In conclusion, the growing interest in this form of treatment seems to be fully justified by the results obtained to date, although more efficacy and dosing studies are required.

Preoperative concomitant radiochemotherapy in squamous cell carcinoma of the esophagus: results of a study of 56 patients

PURPOSE

Today the prognosis for patients with esophageal carcinoma still remains quite poor. In the last few years interesting results have been obtained by associating radio- and chemotherapy with or without surgery with this type of cancer. In this work we report the results of concomitant radio- and chemotherapy in a split-course schedule preceeding surgery for the treatment of squamous cell carcinomas of the esophagus.

METHODS AND MATERIALS

Fifty-six patients with squamous cell carcinomas of the esophagus were treated between April 1989 and September 1993 in the Centre Hospitalier Universitaire in Brest, France with two courses of preoperative concomitant radiochemotherapy, separated by a 2-week interval, and followed by surgery (each course 18.5 Gy in five fractions, days 1-5 with continuous infusion 5-fluorouracil (5-FU) 800 mg/m2 days 1-5 and cisplatinum 70 mg/m2 day 2). Patients who had responded well to preoperative treatment (response > 50%) received four more courses of chemotherapy alone. The two patients who were not operated and those with palliative surgery received a third course of radiochemotherapy (radiotherapy 12 Gy in five fractions, days 1-5).

RESULTS

Fifty-four patients were operated on. Twenty-one showed histological complete response at surgery (37.5% of the whole group). Actuarial survival for the 56 patients was 55% at 3 years and 30% at 4 years, with a median survival of 37.4 months (40.4 months for complete responders to preoperative treatment). Toxicity of preoperative concomitant radio-chemotherapy was low (5-FU had to be stopped in one patient because of cardiac rythm disturbances and in another patient because of aplasia Grade 4 associated with infection after the first course). Postoperative mortality was 11% (six patients).

CONCLUSION

This combination of preoperative radiochemotherapy followed by surgery seems to improve both response rates and survival in patients with esophageal cancer when compared with previous patients treated with surgery alone in our hospital or with results found in literature and it warrants further studies.

Anterior chemotherapy in esophageal cancer

Front loading chemotherapy using methotrexate (200 mg/m2) alone or methotrexate (200 mg/m2) with cisplatin (20 mg/m2 daily for 5 days) was used in epidermoid carcinoma of esophagus. Evaluation after two courses showed objective response of 50% or greater in 48% of patients with methotrexate alone. Response rate was increased to 76.2% with addition of cisplatin to methotrexate. Small lesions (less than 10 cm) showed better response as compared to advanced cases. Therapy was generally well tolerated and good palliation was obtained even after the first course. Postchemotherpy treatment either with surgery or radiotherapy was tolerated without any major complications. The data confirm the short-term usefulness of initial chemotherapy with methotrexate and cisplatin in esophageal cancer. Results of prolonged follow-up will help to evaluate the role of front loading chemotherapy on long-term survival.

Relationship between the radiologic features of esophageal cancer and the local control by radiation therapy

In order to predict the possibility of local control of esophageal cancer by radiation therapy, the relationship between the x-ray findings before and after irradiation and the histologic radiation effect obtained from the surgically resected esophagus was analyzed in 130 cases irradiated preoperatively during the period 1971 through 1980. In the superficial or proliferative type in x-ray image before treatment, the local control was obtained in 46.5% of the cases with the dose of 40 Gy, whereas in the ulcerative or infiltrative type, in 21.8%. The barium examination performed after irradiation was more useful to evaluate the radiation effect than that before treatment. In cases with a marked radiation effect after irradiation, the frequency of local control reached 76.9%. On the other hand, the local control remained 11.9% in cases with no or poor radiation effect. The results obtained by the preoperatively irradiated cases were applied to the analysis of 119 cases irradiated radically during the period 1965 to 1980. Almost the same results were also acquired in radically irradiated cases. The degree of radiologic and histologic radiation effect on the primary tumor was closely related to the long-term survival rate of the patient.

Particle radiation therapy

Current interest in attempting to identify any therapeutic advantages of beams of heavy particles (heavier than electrons) over photons is based on differences in physical absorption and radiobiologic interactions. The article discusses: dose distributions in tissue, which are markedly different for particles than for high energy photons and so may be clinically advantageous for the former; differences in radiobiologic responses, which could lead to increased tumor cell killing and a possible increase in the therapeutic ratio for particles; clinical experience to date; directions for and impediments to future research.

Clinical evaluation of neutron beam therapy. Current results and prospects, 1983

Some 9000 patients throughout the world have been treated by some form of neutron beam therapy. These include patients with advanced nonresectable tumors in many different sites treated with a variety of neutron beam generators varying widely in beam energy. Protocols were largely nonrandomized and included both mixed beam studies (neutrons + photons) and neutrons alone in varying doses. In spite of wide variation in equipment, treatment technique, and philosophy, some consistent trends have been identified: (1) in general, the neutron results have been at least as good as those of the photon controls measured in terms of local control, although the incidence of significant side effects have been higher; (2) in none of the randomized studies conducted so far, largely comprising epidermoid carcinomas of the head and neck, has a clear survival advantage for neutrons over photon controls been demonstrated at a statistically significant level; (3) results with mixed beam studies have been uniformly equivocal, with marginally significant differences in favor of the experimental groups compared with the photon controls; (4) adenocarcinomas of the gastrointestinal tract (GI) tract, including tumors of the salivary gland, pancreas, stomach, and bowel, appear to be responsive to high linear energy transfer (LET) radiation; (5) nonepidermoid, radioresistant tumors (sarcoma of bone and soft tissue and melanoma) yield a consistantly high local control rate, with neutron irradiation strikingly superior to those reported with photon therapy; and (6) in the central nervous system, both normal tissues and tumors appear to be exceptionally sensitive to neutron irradiation, therapeutic ratios are small, and the prospect of cure remains remote. It is concluded that neutrons are efficacious for certain specific tumor types, but that essentially new study designs, based on nonrandomized matched case comparisons, will be required to prove the merit of the new modality.