Late effects of hyperfractionated-radiotherapy for head and neck cancer--in response to Drs. Withers and Taylor, IJROBP 32:887-888; 1995

Nonstandard Fractionation Schedules in Radiation Therapy of Head and Neck Cancer: A Review

The authors present an updated review of the clinical trials on hyperfractionated and accelerated fractionation schedules in radiotherapy of head and neck cancer. The available results in terms of survival and local control, and acute and late toxicity data are summarized in order to show the current status of this research field. The new breed of fractionation schedules that are on study, designed on the ground of new rationales, are presented as well. Finally, an introductory overview of combination therapy including non standard fractionation radiotherapy associated with chemotherapy is reported70.

Dose escalation using twice-daily radiotherapy for nasopharyngeal carcinoma: does heavier dosing result in a happier ending?

PURPOSE

To present our experience using a twice-daily radiotherapy (RT) technique, including hyperfractionated and accelerated-hyperfractionated RT, on nasopharyngeal carcinoma (NPC) patients. The dose to the primary tumor was increased in the hope that local control could be increased without the cost of increased late complications. We analyzed acute and late complications and local control and compared the results with the results of NPC patients treated during the same period using conventional once-daily RT.

METHODS AND MATERIALS

Between October 1991 and July 1998, 222 histologically confirmed, Stage M0, previously unirradiated NPC patients completed RT at our hospital. Most patients had American Joint Committee on Cancer (AJCC) 1992 Stage III and IV disease. Among them, 88 received altered fractionated, twice-daily RT; 76 patients received hyperfractionated RT and 12 accelerated-hyperfractionated RT. The remaining 134 patients received a conventional once-daily regimen. Hyperfractionated RT was delivered using 120 cGy b.i.d. separated by 6-h intervals throughout the course. For the accelerated-hyperfractionated patients, 160 cGy b.i.d. was given, also at 6-h intervals. The median dose in the twice-daily group was 7810 cGy (range 6840-8200). In the once-daily regimen, RT was delivered using 180-200 cGy q.d. The median tumor dose to the primary tumor was 7000 cGy (range 6560-8100) given during about 8 weeks. The median follow-up time was 70.5 and 72 months for the twice-daily and once-daily groups, respectively.

RESULTS

The incidence of acute toxicities was higher in the twice-daily group with more severe mucositis and moist desquamation than in the once-daily group. Both groups had a similar incidence of late complications, except for 3 cases of temporal lobe necrosis in the twice-daily group, all in patients treated with 160 cGy. No difference was noted in recurrence-free local control between the two groups when the individual T stage was compared using AJCC 1992 or 1997 criteria (p = 0.51 and 0.59, respectively). The 5-year local control rate for T1-3 (AJCC 1997) was 93.2% for the twice-daily group and 86.4% for the once-daily group (p = 0.45). In Stage T4 (AJCC 1997) patients, the local control rate dropped drastically to 43.5% and 36.9% for the twice-daily and once-daily groups, respectively. The overall neck control rate at 5 years was 87.3% and 80.3% for the twice-daily and once-daily patients, respectively (p = 0.16). The overall locoregional control rate was 82.7% for the twice-daily group and 66.6% for the once-daily group. The difference was again not statistically significant, but showed a tendency in favor of the twice-daily regimen (p = 0.055). Locoregional failure occurred mainly in Stage T4 patients with central nervous invasion for whom local control was particularly poor, with a failure rate of about 60%.

CONCLUSION

The present data suggest that NPC patients can be safely treated using a 120-cGy twice-daily program with a 6-h interval up to 8000 cGy. The accelerated-hyperfractionated technique is not recommended. A large discrepancy in local control between patients with T1-3 and T4 disease was noted. For T1-3 disease, an excellent local control rate >90% was achieved using the twice-daily regimen. In contrast, failure in the T4 patients was as high as 55% in the twice-daily group and reached 65% in the once-daily group. More rigorous treatment is needed using either additional dose escalation or other strategies for T4 NPC patients. With a dose escalation of 1000 cGy using 120-cGy twice-daily RT, a trend toward better locoregional control and disease-specific survival was noted in the twice-daily group. Whether this difference was truly the result of an increased dose needs additional confirmation in studies with larger patient numbers.

Influence of interfraction interval on the efficacy and toxicity of hyperfractionated radiotherapy in combination with concurrent daily chemotherapy in stage III non-small-cell lung cancer

PURPOSE

To investigate the influence of the interfraction interval (IFI) on treatment outcome and toxicity in hyperfractionated (HF) radiotherapy (RT) for Stage III non-small-cell lung cancer.

METHODS AND MATERIALS

Data for 301 patients treated with 1.2 Gy b.i.d. to a total of 69.6 Gy and concurrent chemotherapy in our 3 prospective studies were analyzed. The chemotherapy regimen was either (1) 50 mg each of carboplatin and etoposide (CE) given on RT days (163 patients) or (2) 30 mg of CE on RT days and 100 mg of CE on Saturdays and Sundays during the RT course (138 patients). An IFI of 4.5-5 h or 5.5-6 h had been nonrandomly assigned for each patient, and this interval was kept throughout the treatment.

RESULTS

No difference was observed in treatment outcome due to the chemotherapy protocol, and the 2 groups were combined. Patients treated with the shorter IFI had a better local control rate (38% at 5 years) and survival rate (30% at 5 years) than those treated with the longer interval (23% and 14%, respectively; p < 0.001). However, female patients and those with a high Karnofsky performance status score (KPS), weight loss of < or =5% in the previous 6 months, or Stage IIIA disease had been more often treated with the shorter IFI, and these characteristics were associated with better treatment outcome. In multivariate analysis, only gender, KPS, and weight change proved to be significant prognostic factors influencing both local control and survival, and the effect of IFI was not significant. The incidence of Grade 4 acute esophagitis tended to be higher in the shorter interval group (p = 0.072), but there were no differences in the incidence of late or other acute RT-related toxicities between the 2 groups.

CONCLUSIONS

The possible influence of the IFI on local control and survival could not be verified using multivariate analysis. To better understand the influence of the IFI, randomized studies with more patients and wider ranges of intervals (e.g., 5 h vs. 8 h) seem to be necessary.

Toxicity in head and neck cancer: a review of trends and issues

The quest for improved fractionation and combined modality regimens in head and neck cancer has also yielded progressively higher rates of toxicity. Time compression of dose delivery in accelerated fractionation has produced high rates of severe mucositis including the early stoppage of two randomized trials. The addition of chemotherapy has introduced systemic toxicity and can exacerbate local tissue reactions when used concurrent with radiotherapy. Mucositis is recognized as the principal impediment to efforts at further treatment intensification. The development and utilization of standardized toxicity grading criteria and accepted reporting standards has lagged toxicity production, impeding a full appreciation of the true extent of both acute and late toxicity. Objective data regarding acute and chronic effects on organ function are also sorely lacking. A better characterization of the frequency, severity, and duration of the various toxicities encountered in head and neck cancer will also allow the rational development of toxicity interventions. New methods are needed to summarize the global or aggregate toxicity of a treatment program. Further research into the assessment and analysis of toxicity is not only crucial to improvements in quality of life (QOL), but perhaps, improved rates of disease control as well.

Results and prognostic factors in the retreatment of locally recurrent nasopharyngeal carcinoma

PURPOSE

To review the results and evaluate the prognostic factors in the retreatment of locally recurrent nasopharyngeal carcinoma.

METHODS AND MATERIALS

We reviewed the records of 74 patients with locally recurrent nasopharyngeal carcinoma treated at the University of California, San Francisco between 1957 and 1995. The histologic types included squamous cell carcinoma in 6 (8.1%), nonkeratinizing carcinoma in 48 (64.9%), and undifferentiated carcinoma in 20 (27%) cases. The site of recurrence was in the primary in 46 (62.2%), in the neck nodes in 20 (27%), and in both sites in 8 (10.8%) patients. The recurrent disease was Stage I in 10 (13.5%), Stage II in 16 (21.6%), Stage III in 20 (27%), and Stage IV in 28 (37.9%) patients. Thirty-seven (50%) patients developed recurrence within 2 years and 58 (78.4%) within 5 years after initial treatment. Radiotherapeutic techniques used in the retreatment of primary recurrence consisted of external beam radiotherapy (EBRT), intracavitary brachytherapy, heavy-charged particle beam, and gamma knife, alone or in combination. Reirradiation doses ranged from 18 to 108 Gy, with a median dose of 60 Gy. Treatment of recurrent neck nodes consisted of radical neck dissection (RND) +/- intraoperative radiotherapy (IORT), or EBRT +/- hyperthermia, or chemotherapy +/- hyperthermia. Chemotherapy was used in 22 (30%) patients. Median follow-up was 20 months (range: 2 to 308 months).

RESULTS

The 3-, 5-, and 10-year actuarial overall survival following retreatment were 49, 37, 18%, respectively. Thirty-six patients (49%) were free of further local-regional recurrence after retreatment. The 3-, 5-, and 10-year local-regional progression-free rates were 52, 40, and 38%, respectively. On univariate analysis, histologic type (p < 0.0001), interval to recurrence (p = 0.034), and treatment modality for early-stage disease (p = 0.01) were significant prognostic factors for overall survival, with age being marginally significant (p = 0.053). For local-regional progression-free rate, only histology was significant (p = 0.035). On multivariate analysis, age (p = 0.026), histology (p = 0.015), and interval to recurrence (p = 0.030) were significant for overall survival, and only histology (p = 0.002) and presence of complications (p = 0.016) were significant for local-regional progression-free rate. Of the 64 reirradiated patients, late complications were documented in 29 (45%) patients. The late complications were permanent in 21 (33%) and severe in 15 (23%) patients.

CONCLUSION

Retreatment using radiotherapy alone or in combination with other treatment modalities can achieve long-term local-regional control and survival in a substantial proportion of patients with locally recurrent nasopharyngeal carcinoma. Age, histology, and interval to recurrence were independent prognostic factors for overall survival, but only histology and presence of complications were significant for local-regional progression-free rate.

Lack of influence of sequence of top-up doses on repair kinetics in rat spinal cord

BACKGROUND AND PURPOSE

The rat spinal cord model was used to determine whether repair kinetics changed during a course of fractionated radiotherapy if twice daily doses were given either at the initial or final period of a concomitant boost irradiation schedule.

MATERIALS AND METHODS

The rat cervical spinal cord was irradiated from C2-T2 in 870 animals with top-up doses of three daily fractions of 9 Gy representing 75% of the biologic dose at the ED50 level for white matter necrosis. To simulate concomitant boost protocols, these top-up doses were given either preceding (initial top-up) or following (final top-up) a b.i.d. schedule of 1 Gy/F delivered at 0, 1, 2, 4, 8 or 24 h interfraction intervals. The end point was forelimb paralysis secondary to white matter necrosis.

RESULTS

For interfraction intervals of 0, 1, 2, 4, 8 and 24 h, the initial top-up schedules yielded ED50 values of 18.2, 19.2, 23.7, 21.3, 27.2 and 29.7 Gy, respectively; the corresponding ED50s from the final top-up schedules were 17.5, 19.0, 20.7, 21.2, 26.9 and 30.3 Gy, respectively. A 10% reduction in the ED50 value from pooled data was observed when the interfraction interval was reduced from 24 (ED50 = 30.3 Gy) to 8 h (ED50 = 27.1 Gy). Fitting the incomplete repair (IR) version of the LQ model with mono-exponential repair kinetics gave alpha/beta values of 1.4 and 1.5 Gy, and similar repair half-times of 4.3 and 5.0 h for the initial and final top-up experiments, respectively. The IR model with bi-exponential repair kinetics did not provide a better fit to the data.

CONCLUSIONS

We conclude that the sequence of top-up doses has no apparent influence on radiation sensitivity or repair kinetics in the rat spinal cord. The clinical implication is that the interfraction interval but not the timing of the boost is a critical determinant of spinal cord tolerance in concomitant boost protocols.

Hyperfractionation: where do we stand?

Hyperfractionation is generally expected to allow an escalation of total dose, thereby increasing tumour control rate, without increasing the risk of late complications. The purpose of this review is to assess the empirical evidence for this therapeutic gain from hyperfractionated radiotherapy. Although extensive clinical data have been accumulated until now, especially on treatment of head and neck cancer, the line of evidence is not consistent. The present analysis indicates that the dose per fraction generally used in standard radiotherapy is already a good choice.