Multiple daily fractions in radiotherapy

Hyperfractionated, twice-a-day, radiotherapy may decrease IQ deterioration due to prophylactic cranial irradiation in childhood acute lymphoblastic leukemia: a radiobiological analysis

High cure rates in childhood acute lymphoblastic leukemia (ALL) are being achieved with aggressive systemic chemotherapy and treatment to sanctuary sites including prophylactic cranial irradiation. However, IQ deterioration is a dreaded complication of prophylactic cranial irradiation. IQ deterioration is a late sequela. Since there is evidence--both radiobiological and clinical--to suggest that acute tissue (including tumor) response and late tissue response can be separated by hyper-fractionation, we propose a twice-a-day radiotherapy in prophylactic cranial irradiation of childhood ALL to decrease delayed toxicity. Analysis based on current radiobiological models favors such a treatment scheme. However, only a prospective clinical trial can confirm whether IQ deterioration can be prevented or decreased with hyper-fractionated radiotherapy.

Twice-daily anesthesia in infants receiving hyperfractionated irradiation

Four children ranging in age from 6-30 months were treated with twice-daily (BID) radiation therapy under general anesthesia with a 5-6 hr treatment interval. Anesthesia was accomplished with sodium thiopental administered intravenously (IV) by bolus injection. This as followed by continuous drip infusion of sodium thiopental in a few instances where more prolonged anesthesia was required. Children received an initial formula feeding 6 hr before their first treatment and were subsequently kept NPO (nothing by mouth) until they recovered from their second anesthesia. Recovery from thiopental was rapid and children were ready for a normal feeding within 1-1 1/2 hr of the second treatment. No parenteral feedings were required in any of these patients. Children maintained their weight during courses of radiation therapy which ranged between 19 and 43 elapsed days. There were no radiation-related treatment breaks. One child experienced two hypotensive episodes during anesthesia which responded rapidly to intravenous atropine. No other anesthetic complications occurred. This experience demonstrates that hyperfractionated radiation therapy can be safely delivered in infants requiring general anesthesia for immobilization. We feel that sodium thiopental is the anesthetic of choice in this setting because of the short duration of action and consequently rapid post-anesthesia recovery which makes it possible to achieve adequate nutrition with oral feedings alone.

Decreased bone growth arrest in weanling rats with multiple radiation fractions per day

The relative growth arrest caused by fractionated irradiation delivered in single or multiple daily fractions was studied in weanling rats. Twenty-two day old male rats were treated to a total dose of either 20 or 25 Gy in five consecutive days to the distal femoral and proximal tibial epiphyses of the right and left leg. For each dose three treatment groups were followed for longitudinal tibial growth as measured on serial radiographs: (a) no treatment, (b) 5 fractions in 5 days or (c) 10 fractions in 5 days. Tibial length was significantly greater in the legs treated with twice-daily fractions (TDF) as compared with single daily fractions (SDF) with 23% and 27% sparing of growth arrest (at 200 days) in legs treated to total doses of 20 and 25 Gy respectively (p less than 0.001). This appeared to result from a continuously greater rate of growth during the first 40-50 days following TDF irradiation as compared with SDF. These data suggest that hyperfractionation may provide a means of reducing growth deficits in children when skeletal growth centers must be included in the irradiated volume.

High activity iodine 125 endocurietherapy for recurrent skull base tumors

Experience with endocurietherapy of skull base tumors is reviewed. We present our cases of recurrent pituitary hemangiopericytoma, radiation-induced recurrent meningioma, recurrent clival chordoma, recurrent nasopharyngeal cancer involving the cavernous sinus, and recurrent parotid carcinoma of the skull base which were all successfully retreated with high-activity 125iodine (I-125) permanent implantation.

Repair of sublethal radiation injury after multiple small doses in mouse kidney: an estimate of flexure dose

Functional kidney damage in mice was measured after a series of fractionated X-irradiations. Doses per fraction of 0.75-12.5 Gy were given as 2, 5, 10, 30, 40, 60, or 80 equal doses in a total treatment time of 4 weeks. Renal function (measured by clearance of 51CrEDTA or hematocrit levels) deteriorated progressively, in a dose related manner, from 20 to 46 weeks after the start of treatment. The changes in renal function versus time were fitted by a polynomial regression through all data and interpolated values for 51CrEDTA clearance were then calculated at 30 and 40 weeks after treatment. Steep dose response curves were obtained and these were used to calculate isoeffective doses for the different fractionation schedules. There was a marked increase in total isoeffective doses from 2-30 fractions and these data were well described by a linear quadratic (L.Q.) expression for damage with an alpha/beta ratio of 2.3 +/- 0.2 Gy. There was only a slight increase in the total isoeffect dose as the size of the dose per fraction was decreased below 2 Gy and the measured isoeffect doses after 40 to 80 fractions were lower than predicted on the basis of an L.Q. model assuming complete repair between successive irradiations. The flexure dose for mouse kidneys irradiated 3 times per day was, effectively, 1 to 2 Gy and hyperfractionation using lower doses per fraction did not lead to significant, additional repair.

Radiation-induced neoplasms of the brain

The histopathology of two patients with radiation-induced neoplasms of the brain following therapeutic irradiation for intracranial malignancies is described. The second neoplasms were an atypical meningioma and a polymorphous cell sarcoma, respectively. They occurred 12 and 23 years after irradiation (4000 rad), within the original field of irradiation. In both cases, the radiation-induced tumors were histologically distinct from the initial medulloblastomas. Both patients were retreated with local irradiation using permanent implantation of radioactive iodine-125 seeds.

Hyperfractionated photon radiation therapy in the treatment of advanced squamous cell carcinoma of the oral cavity, pharynx, larynx, and sinuses, using radiation therapy as the only planned modality: (preliminary report) by the Radiation Therapy Oncology Group (RTOG)

From August 1979 to June 1983, the RTOG conducted a prospective Phase III study that compared a standard schedule with five fractions per week of 180 to 200 cGy per day to a total dose of 6600-7380 cGy, with a hyperfractionation regimen consisting of two fractions of 120 cGy per day, separated by a rest period of 3 to 6 hours for a total of 6000 cGy. A total of 210 patients were entered, of which 187 are analyzed. Complete initial tumor clearance in the head and neck was achieved by radiotherapy in 61% of the patients assigned to the standard schedules and in 59% of those assigned to the continuous hyperfractionation schedule; surgical salvage contributed towards achieving complete response in 5% and 7% of patients, respectively. The Kaplan-Meier estimates for loco-regional control of tumor at 1 and 2 years was 39% and 29% for the standard schedules, and 43% and 30% for the hyperfractionation schedule. The endpoints examined to evaluate therapeutic effects do not indicate that the stated hyperfractionation schedule is different than the standard RTOG treatment schedule for head and neck cancer. Acute normal tissue reactions appear to be more severe with the hyperfractionation schedule but the incidence of late reactions is similar in both groups. There is a tendency toward more severe acute reactions when the interval between the two fractions per day is 4.5 hrs or less in comparison to intervals longer than 4.5 hrs.

Solid tumor models for the assessment of different treatment modalities: XXIII. A new approach to the more effective utilization of radiotherapy alternated with chemotherapy

This study with the rat hepatoma 3924A demonstrated the marked improvement in tumor cure rates and control of tumor growth that can be achieved by the addition of cyclophosphamide (CP) to multiple fractions of radiation per day (MFD) schedules given intermittently. MFD radiation was delivered over a 2-day period followed by CP (150 mg/kg or 0.9 g/m2) 1 day later; this combined course was repeated at 11-day intervals (to allow for gastrointestinal tract and bone marrow recovery) for a total of 3 courses over a 23-day period. Cure rates of 30, 50 and 60% were achieved with total radiation doses of 4500, 6000 and 7500 rad, respectively, when the MFD radiation was given with CP. No cures and no complete responses were realized when the same intermittent MFD schedules for radiation were employed up to 9000 rad without CP. Other groups of 10 animals each were treated with daily fractions of 100, 150, 188, 250 and 375 rad given on days 0-9, 11-20 and 22-31. A 150 mg/kg or 0.9 g/m2 dose of CP was given after each course of daily radiation on days 10, 21 and 32 in the combined treatment groups. No complete responses or tumor cures occurred with radiation alone given daily for total radiation doses, which were increased from 3000 to 11,250 rad. Only the highest radiation dose given, 375 rad per day to a total of 11,250 rad, resulted in a complete response rate and tumor cure rate of 50% when CP was added. The addition of CP to the daily fractionation schedules reduced the total dose needed to give a growth delay of 100 days by 39% (5600 rad versus 9200 rad). The addition of CP to the intermittent MFD schedules further reduced the total dose needed to give a growth delay of 100 days to 4200 rad. Major improvements in some types of cancer treatment may be realized if we can develop clinical protocols for the alternate use of chemotherapy and radiotherapy as we have done successfully in our experimental program. The finding that intermittent MFD radiation schedules are as effective as daily schedules when given alone suggests that greater flexibility of patient management in clinical radiotherapy may be possible without a major loss of therapeutic effectiveness. These alternated fractionated schedules offer the possibility of optimizing treatment in terms of patient convenience and economy as well as the potential for improving the effectiveness of the interaction of radiotherapy with radiosensitizers, radioprotectors, and hyperthermia in addition to chemotherapy.

New frontiers in the treatment of lung cancer

Surgical resection still is the only significant curative approach in nonsmall cell lung cancer. Recent surgical experience indicates that a modest decrease in the death rate from bronchogenic carcinoma may occur in three general areas: (1) the detection and treatment of radiographically occult squamous cell carcinoma; (2) the combination of adjuvant chemotherapy and surgical excision in selected patients with small cell carcinoma; and (3) surgical resection and postop irradiation of patients with hilar and mediastinal lymph node metastases. At the time of diagnosis, 80 to 85% of the patients present with unresectable lung cancer. These patients may benefit from other modalities of therapy, i.e., radiotherapy, chemotherapy, or immunotherapy. Failures following radiotherapy in unresectable nonsmall cell lung cancer are due to (1) distant metastasis, (2) local region failure, and (3) local and distant failure. To increase the local control, new methods of treatment have been tried, such as hyperfractionation of radiotherapy and the use of 131I antiferritin immunoglobulin. The development of effective systemic chemotherapy is necessary to treat metastatic bronchogenic carcinoma. The response rate to chemotherapeutic agents is substantially lower in nonsmall cell carcinoma than in small cell carcinoma. Investigation is ongoing to assess the effectiveness of new antitumor drugs used alone, in combination with other drugs, or combined with other modalities for the treatment of bronchogenic carcinoma.

Solid tumor models for the assessment of different treatment modalities. XXII. The alternate utilization of radiotherapy and chemotherapy

Major increases in the time between administration of two modalities, radiation and cyclophosphamide (CP), from 1 to 7 days and in the overall time of delivery of 3 courses of combined therapy from 24 to 35 days were carried out in rats with hepatoma 3924A without major loss of therapeutic effectiveness. Cure rates of 50% or greater could be maintained even though treatment was given over much longer time periods. The radiation was given as hyperfractionated, split-course schedules which were devised by increasing the number of 250 rad fractions over a 2-day period. In one series of experiments these 2-day schedules were given at 11-day intervals for 3 courses on days 0 and 1, 11 and 12, 22 and 23; and CP (150 mg/kg) was given 1 day after each of the 3 radiation courses on days 2, 13, and 24. In the second series of experiments radiation was given on days 0 and 1, 14 and 15, 28 and 29; and this was alternated with 3 single doses of CP given 1 week after each of the 3 courses of radiation, on days 7, 21 and 35. Increasing the total radiation dose from 6000 to 7500 rad in the series given CP 1 day after each of three courses of radiation results in an increase in total tumor cure rates from 50% to 60%. The tumor cure rate in the series given CP 7 days after radiation increased from 10% to 70% when the total radiation dose was increased from 6000 to 7500 rad. Increasing the total radiation dose from 6000 to 7500 rad increased the magnitude of the acute skin reaction as well as the duration of recovery. However, the skin reactions for both the 6000 and 7500 rad were acceptable. Host toxicity and normal tissue reaction were within acceptable limits for both modalities. The results of these studies, therefore, indicate that excessive toxicity, one of the major deterrents to the effective combined utilization of these two primary means of cancer management, may be avoided by temporal separation of delivery while maintaining tumor cure rates of 50% or greater.

Short-term variation in labeling index as a predictor of radiotherapy response in human oral cavity carcinoma

In vitro determination of [3H]thymidine labeling index (LI) was carried out on squamous cell carcinomas of the oral cavity from 52 patients before and during radiotherapy. Pretreatment LI values ranged from 0.01% to 50%. After administration of the first 10 Gy in five consecutive daily fractions, a decrease in LI was observed in 39 cases and an enhancement in 13 cases, with an overall median 70% decrease in the initial value. The type of variation induced by radiotherapy was not related to pretreatment LI except for tumors with a very low proliferative activity (LI less than or equal to 1.9%), which all showed a marked increase in LI. Pretreatment LI was not indicative of short- or long-term response to radiotherapy, whereas the variation induced on LI after 10 Gy was related to the clinical outcome. A variation in LI of more or less than 70% was not significantly associated (p = 0.077) with clinical objective response (respectively, 85 and 53%). However, all 8 patients who reached a complete regression, notwithstanding an enhancement or a slight decrease in LI, had a local recurrence within 19 months. Conversely, the probability of disease-free survival was 82% for the 11 patients whose tumors had a significant decrease in LI (greater than or equal to 70%) after the first 10 Gy.

Chordoma: the results of megavoltage radiation therapy

Twenty-four patients with chordoma who received one or more courses of megavoltage radiation therapy following biopsy or incomplete resection were reviewed. The uncorrected survival rate at five years was 62%, and at 10 years was 28%, but most patients had clinically detectable residual chordoma present at the time of death or last follow-up. The duration of symptomatic improvement following irradiation ranged from a few months to 18 years, median 3.5 years. Detailed dose-time and symptomatic response data for 56 patients from this series and from the literature who were treated by conventional daily fractionated megavoltage irradiation show no convincing evidence that symptomatic relief is more likely after high doses than after total doses of only 4000 to 5500 cGy. Patients are rarely cured of chordoma by partial tumor resection and conventional radiation. Four patients received multiple fractions of 100 cGy each day either as retreatment for recurrence, or as initial treatment. Symptomatic responses, and decreases in the size of tumor masses, were seen following total doses ranging from 2000 cGy/20 fractions/5 days/4 X 3 hourly fractions each day to 4000 cGy/40 fractions/12 days/4 X 3 hourly fractions each day. The short duration of follow-up in these patients prevents comparison with conventional fractionation. However, this technique presents one possible new approach for the treatment of chordoma.

Solid tumor models for the assessment of different treatment modalities. XXI. Comparison of different radiation dose schedules alone or in combination with cyclophosphamide

Total radiation (4500 rad) and cyclophosphamide doses (450 mg/kg or 2.7 g/m2) were held constant over a 24-day period in rat hepatoma 3924A using radiation schedules in which 1500 rad were given over a 1- to 2-day period in 1-8 fractions, repeated at 11-day intervals, with or without cyclophosphamide. Reducing the rad per fraction resulted in a reduced incidence of complete tumor response and tumor cures, and a reduction in the magnitude of skin response. Cure rates were 40, 10, 0, and 0%, respectively, for the 1500, 750, 500, and 250 rad per fraction groups without cyclophosphamide. When the 1500, 750, 500, 375, 250, and 188 rad per fraction groups were given 150 mg/kg cyclophosphamide day 1 after radiation, major increases occurred in tumor cures, with the cure rates being 80, 80, 80, 70, 60, and 50%, respectively. The addition of cyclophosphamide did not significantly alter skin reaction to radiation. The higher rad per fraction schedules were more effective in controlling metastatic dissemination when radiation was used alone. The addition of cyclophosphamide markedly reduced metastatic dissemination in both high and low-dose per fraction schedules. Optimal treatment levels were estimated from analysis of fitted response surfaces, and the quantitative interrelationship between normal tissue reaction, probability of tumor cure, and associated relative hazard to the host estimated from the results of these analytical methods. Hyperfractionated radiation dose schedules with dose/fraction in the clinical range combined with cyclophosphamide can significantly increase the therapeutic ratio and prevent metastatic dissemination compared with radiation alone as a result of the increased effectiveness of combined modality therapy on the tumor, without a concomitant increase in normal tissue reaction.

Malignant astrocytoma: hyperfractionated and standard radiotherapy with chemotherapy in a randomized prospective clinical trial

A prospective randomized trial of 157 patients with malignant astrocytoma (Grade III or IV) was carried out at a single institution. The minimization technique ensured balanced distribution of prognostic factors between the treatment groups. All received oral lomustine (CCNU, 80 mg/m2) six weekly and hydroxyurea (HU, 3.5 gm/m2 over 5 days) three weekly, for one year or until recurrence, with doses adjusted for myelosuppression. Patients were randomized to daily (5000 rad in 25 fractions (fr) in 5 weeks) or Q3h (every 3 hours) Cobalt 60 irradiation (3600-4000 rad in 36-40 fr of 100 rad each, given 4 fr per day at 3-hour intervals over two weeks) Steroid therapy (up to 16 mg day dexamethasone) was permitted. Complications were moderate and equivalent in the two groups. No significant survival or toxicity differences were seen between the two groups. Age, initial performance status, and extent of surgical resection were found to be significant (P less than 0.01) prognostic factors for survival. Median survival of the whole group was 48 weeks with a minimum follow-up of one year. There was no advantage to large radiation fields. The hyperfractionation and daily regimens had similar efficacy and toxicity. Hyperfractionation with chemotherapy offers a useful alternative approach in the management of this disease.