New horizons in radiation oncology. Presidential address delivered on April 13, 1978 at The British Institute of Radiology Joint meeting and Annual Congress held at the RIBA, London W1

How radiation oncology emerged as a discipline in Finland

The news about the discovery of Röntgen's new rays spread over Finland quite early, and the first Finnish writing about the rays appeared in February 1896. The first x-ray machine was installed in 1897. Proper training of radiologists began, however, at a comparatively late date. For a long time the position of radiologists remained a subordinate one. Radiology had the nature of a spare time hobby, because in most hospitals surgeons treated x-ray machines as a sideline. Because of this, scientific research work was delayed. The specialty of x-ray diagnosis and therapy was, however, established in 1921, and the Finnish Society of Radiology was founded in 1924. The first radiotherapy department with its own beds was opened in 1936 in Helsinki. In 1950, the first professor of medical radiology was appointed at the University of Helsinki. The Finnish Cancer Society played an important role in developing the radiotherapy net in the country by supplying cobalt devises and auxiliary hospital activities in the 1960s. In the early 1960s roentgen diagnosis and radiotherapy were separated into two distinct disciplines. There are now five medical faculties with chairs in radiation oncology. The country is divided into five regions for cancer care. The managing groups in each region are headed by the professor of radiotherapy and oncology. The radiation oncologists in Finland are involved in diagnosis and staging of cancer and are responsible for radiation therapy, chemotherapy and hormones. They are responsible for follow-up of treated patients, their own wards, and the general care of their patients.

Prospective trial of combined hyperfractionated radiotherapy and bronchial arterial infusion of chemotherapy for locally advanced nonsmall cell lung cancer

PURPOSE

This article is a prospective trial of hyperfractional radiotherapy with bronchial arterial infusion of anticancer drugs to treat locally advanced bronchogenic cancer. The treatment results, the complications of bronchial arterial infusion, the failure patterns, the relationship of technical aspects of delivery of radiotherapy, and the protocol of anticancer drugs are presented.

METHODS AND MATERIALS

One hundred and twenty-six patients with locally advanced bronchogenic cancer, treated from January 1988 to January 1990, were divided randomly into four groups in our hospital. Group 1: combination of hyperfractional radiotherapy with bronchial arterial infusion of anticancer drugs (30 cases); Group 2: combination of conventional radiotherapy with bronchial arterial infusion of anticancer (33 cases); Group 3: combination of systemic chemotherapy and split-course radiotherapy (33 cases); Group 4: conventional radiotherapy only (30 cases).

RESULTS

All the patients were followed for 3 years. The 1-year survival rates for Groups 1, 2, 3, and 4 are 80, 63.6, 48.5, and 30%, respectively. The 2-year survival rates for Groups 1, 2, 3, and 4 are 23.3, 15.15, 9.1, and 6.6%, respectively. The 3-year survival rates for Groups 1, 2, 3, and 4 are 10, 3.3, 0, and 0%, respectively.

CONCLUSION

This study demonstrated that the combination of hyperfractional radiotherapy with bronchial arterial infusion anticancer drugs can be performed safely and effectively for locally advanced bronchogenic carcinoma.

A phase I/II study to evaluate accelerated fractionation via concomitant boost for squamous, adeno, and large cell carcinoma of the lung: report of Radiation Therapy Oncology Group 84-07

PURPOSE

A Phase I/II trial was conducted by the Radiation Therapy Oncology Group from 1984 to 1989 for 355 evaluable patients with non-small-cell lung cancer to assess tolerance to and efficacy of accelerated fractionation irradiation via concomitant boost.

METHODS AND MATERIALS

"Large" fields (primary tumor and locoregional lymph nodes) received 1.8 Gy followed after 4 to 6 hr by 1.8 Gy two to three times weekly to reduced "boost" fields (primary and involved nodes only). The total doses escalated during the study and started with 63 Gy in 5 weeks (45 Gy "large" field and 18 Gy "boost") for 61 patients. After follow-up for ongoing toxicity assessment, the total dose was increased to 70.2 Gy in 5.5 weeks (50.4 Gy "large" field and 19.8 Gy "boost") for the next 180 patients. The last 114 patients received 70.2 Gy in 5 weeks (45 Gy "large" field and 25.2 Gy "boost").

RESULTS

Pretreatment patient characteristics were well balanced between the three treatment arms. Grade 3 acute toxicity was 7% for the 63 Gy arm; it was 14% and 17% for the two 70 Gy arms. Grade 4 or greater acute toxicities (esophagitis and pneumonitis) were 2 to 3% for all three arms. Late toxicities ranged between 5 and 9% (> or = Grade 3) and 0 to 2% (> or = Grade 4), not statistically different among the three arms. There was no difference between the three regimens in median survival (9 months) or 1-year survival (39 to 44%). However, the 2-year survivals ranged from 16% (63 Gy) to 21% ("shortened" 70.2 Gy). Among 176 patients who had the same criteria as Cancer and Leukemia Group B protocol 84-33 (American Joint Committee on Cancer Staging, 1984, Stage III; Karnofsky performance status 70 to 100; < 6% weight loss), the 2-year survival rates ranged from 18 to 22%.

CONCLUSION

Concomitant boost accelerated fractionation irradiation regimens for non-small cell lung cancer may offer improved long-term survival without enhanced late toxicity. While acute toxicity is somewhat increased, further refinement of the relationship of "large" to "boost" field doses may improve the therapeutic ratio. Further Phase I/II testing seems justified and necessary, before concomitant boost accelerated fractionation irradiation is tested in Phase III trials for NSCLC.

Hyperfractionated radiation and chemotherapy for unresectable localized adenocarcinoma of the pancreas. The Gastrointestinal Tumor Study Group experience

Eighteen patients with unresectable localized adenocarcinoma of the pancreas were treated by a combination of chemotherapy plus hyperfractionated radiation therapy to the pancreas for 4080 cGy with an additional 960 cGy to the pancreatic tumor and a surrounding margin. One hundred and twenty cGy were given twice daily 4 to 6 hours apart. High-energy photon or electron beams were used with treatment planning based on computed tomographic (CT) scans. Patients were given chemotherapy in the form of 5-fluorouracil (5-FU) at 350 mg/m2 on the first 3 and last 3 days of radiation therapy. On day 53, chemotherapy was given that included 600 mg/m2 IV of 5-FU, 1 gm/m2 of streptozotocin, and 10 mg/m2 IV of mitomycin C. The 5-FU and streptozotocin were repeated on days 60, 81, and 88, and the stretozotocin and mitomycin (SMF) cycles were repeated every 8 weeks until progression. Radiation toxicity was generally tolerable with one of 18 evaluable patients having severe nausea and vomiting and two of 18 patients having severe diarrhea. One patient had total liver failure and died 3 months after initiation of therapy. Six patients had severe hematopoietic toxicity during chemotherapy. Overall, the severe toxicity rate was higher (67%) than in previous studies. Median survival was 35 weeks, the 1-year survival rate was 39%, and the patient who survived the longest died at 68 months. Although this schedule of hyperfractionated radiation and chemotherapy was disappointing, combined experimental radiation approaches plus chemotherapy for localized unresectable adenocarcinoma of the pancreas deserve additional research.

The effect of radiation on the growth of normal and malignant human oesophageal explant cultures pre-treated with bleomycin

Since all known chemotherapy and radiation treatments affect normal cells to a certain extent, the establishment of favourable differential sensitivities is fundamental to the success of treatment with a particular agent. This type of information can be gained by animal testing and using cultured cells, but ultimately use of the agent in the patient is the only way to determine the response. We have developed a model for testing the response of oesophageal explants from tumour and surrounding normal tissue in the same patient to chemotherapy and radiation, both singly and in combination. The test allows treatment combinations, time and order of administration of agents to the tissue to be accurately controlled. Cytotoxicity, determined by measuring the area of outgrowth from an explant 2 weeks after plating, is the most useful short-term end-point, although many others are possible. Results showing the differential cytotoxicity of bleomycin with and without radiation in squamous and adenocarcinoma of the oesophagus and surrounding normal tissue from the same patient indicate that tumour cells are relatively resistant to radiation alone, that low levels of bleomycin with or without radiation preferentially spare tumour cells and that high levels, in combination with any dose of radiation tested, but not without radiation, spare the normal cells and give a significantly high amount of relative tumour cell kill. Bleomycin must be added to the cells just before or just after irradiation to obtain the normal-tissue sparing effect. The technique may be a useful method for indicating the best approaches to the optimization of combined therapy regimes.

Radiation-induced outgrowth inhibition in explant cultures from surgical specimens of five human organs

An explant outgrowth technique to determine the radiation response of five different human organs (bladder, oesophagus, colon, breast and thyroid) is described. In each case except thyroid, where malignancies are rare, data are presented for normal and malignant tissue. Results show that variations in response, consistent with those observed in vivo, can be measured. Tumours were in all cases highly resistant to radiation relative to their corresponding normal tissue. Possible reasons for this are discussed. The method may prove useful in the prediction of the radiobiological response for tumour and surrounding normal tissue where post-operative therapy is planned.

The effect of hydralazine on the tumor cytotoxicity of the hypoxic cell cytotoxin RSU-1069: evidence for therapeutic gain

The effect of the vasodilator hydralazine on both the tumor and systemic toxicity of RSU-1069 has been evaluated in C57B1 mice bearing Lewis lung tumors. The results obtained indicate that both hydralazine and RSU-1069 are cytotoxic to the Lewis lung tumor on their own. However, administration of hydralazine (5 mg/kg PO) at times up to either 3 hr before or 3 hr after RSU-1069 (0.1 mg/g IP) results in a level of cell killing greater than expected from additive effects. This potentiation by hydralazine was observed with doses of RSU-1069 from 0.01 to 0.1 mg/g. The results obtained using excision assays were confirmed using in situ growth delay as the endpoint. Growth delay (+/- s.e.m.) values for tumors to double in volume of 1.5 (+/- 1.2), 2.0 (+/- 1.3) and 6.0 (+/- 0.9) were obtained for hydralazine (5 mg/kg PO) alone, RSU-1069 (0.1 mg/g IP) alone and for hydralazine administered at the same time as RSU-1069 respectively. In contrast to the potentiating effect of hydralazine on the tumor cytotoxicity of RSU-1069, it had no significant effect on the systemic toxicity of RSU-1069 as measured by LD50/30d. No detailed studies to examine the mechanism responsible for the potentiation of tumor cytotoxicity have been performed in the present study. However, the results obtained would be consistent with previous reports that vasodilators such as hydralazine can selectively reduce tumor blood flow and thus oxygenation. Such reduced tumor oxygenation would increase the cytotoxic effects of RSU-1069 which is known to be more toxic to cells at reduced oxygen levels.

Hyperfractionation in the radiation therapy of unresectable non-oat cell carcinoma of the lung: preliminary report of a RTOG Pilot Study

Patients with localized unresectable non-oat cell carcinoma of the lung were treated by supervoltage radiation therapy to the primary tumor, mediastinum and supraclavicular lymph nodes with 50.4 Gy, 42 fractions of 1.2 Gy, twice daily, 4 to 6 hours apart, 5 times a week. Small field treatment to the known involved areas of primary and lymph nodes was given from 9.6 to 24 Gy, also with 1.2 Gy, twice daily. One hundred twenty-five patients were entered, three of whom were cancelled and two were ineligible. Of the remaining 120 eligible patients, 10 patients received a dose of 50.4 Gy, 20 received 60.0 Gy, 79 received 69.6 Gy and 11 patients received 74.4 Gy. Of these, nine patients were unable to complete hyperfractionated radiation therapy for various reasons. Treatment was discontinued or stopped in 14 patients because of early death or deterioration of the patient's condition. Four additional patients were found to have unacceptable doses to tumor or normal tissues, for a total of 27 patients with protocol violations. Complete regression occurred in 19% of T1-T3, N0-N2 patients with 9% among T3.3b, T4 or N3 patients. Partial regression was 29 and 41%, respectively. There were six cases of severe and two of life-threatening toxicity, but there were no fatalities attributable to the treatment. Toxicity consisted mainly of pneumonitis and pulmonary fibrosis as well as esophagitis. Median survival of the entire group was 7.2 months, which is consistent with previous experience with the treatment of localized inoperable non-oat cell carcinoma of the lung by radiation therapy. Further study of this method of treatment is warranted.

Patterns of cell loss and repopulation in irradiated cultures of plateau phase C3H 10T 1/2 cells

Patterns of cell loss and repopulation were studied in plateau phase cultures of slowly-cycling, contact-inhibited C3H 10T1/2 mouse fibroblasts following large single, and multiple small doses of 137Cs-gamma rays. A progressive, dose-independent cell loss was apparent within days after irradiation with large single doses, and similar patterns of loss were observed following the start of multifraction irradiations. This progressive cell loss culminated in the loss of integrity of the monolayer of cells, a loss of contact-inhibition, and therefore, an increased rate of cell division. The time of onset of measurable repopulation, and the time required to completely repopulate a culture varied with the number of clonogenic cells present at the time of breakdown of the monolayer. For cultures receiving multiple irradiations over time periods greater than those required for breakdown of the monolayer, repopulation began to occur during treatment, and its rate varied with the average dose per fraction being delivered. Thus, repopulation did not start immediately after the start of irradiation, but needed a triggering event, in this case, a decrease to a critical level in the cell density. Once initiated, repopulation was able to decrease or even eliminate the effectiveness of subsequent doses in reducing the number of viable cells per culture. To the extent that the responses of slowly-cycling, contact-inhibited cells in vitro can be applied to interpret the radiation responses of cell populations in vivo, these results further support the notion that it may be necessary, in some cases, to account for an increasing contribution from repopulation with increasing overall treatment time in dose fractionation isoeffect formulae used for predicting tissue tolerances or tumor control.

Tumor radioresistance in clinical radiotherapy

Tumor radioresistance in clinical radiotherapy implies failure to achieve loco-regional disease control with radiation doses producing an acceptable degree of morbidity. Such radioresistance may be a result of many different causes (biological and technical) which are reviewed in terms of possible remedial actions. Dose response relationships for human cancers suggest that in many sites, tumors are heterogenous with respect to their cure-limiting characteristics. The case is developed that unless the predominant cure-limiting factor can be predicted, little benefit may be seen in trails of new treatment strategies using heterogeneous tumor populations. The fundamental problem of clinical radioresistance is therefore perceived as the inability to predictively identify its cause in the individual patient.

Negative pion depth-dose profile examined by means of HeLa cell-survival curves

HeLa cells were irradiated at liquid nitrogen temperature with negative pions from Nimrod at the Rutherford Laboratory and then assayed for survival of colony-forming ability. Complete dose-response curves were obtained from repeated determinations at 14 different positions along the depth-dose profile and survival curves were fitted to the data by computer programme. A depth-damage profile was thus established in terms of the final slopes of these survival curves. This confirmed the expected RBE value of 1.84 at the ionization peak. Although a value of unity was found in the main plateau region, the "entrance" positions showed significantly higher values.