Similar decreases in local tumor control are calculated for treatment protraction and for interruptions in the radiotherapy of carcinoma of the larynx in four centers

Comparison of acute toxicities in two primary chemoradiation regimens in the treatment of advanced head and neck squamous cell carcinoma

PURPOSE

The optimal dosage and frequency of platinum-based chemoradiotherapy (CRT) regimen for treating advanced head and neck squamous cell carcinoma remains unresolved. This study aims to compare the toxicity and efficacy of weekly versus more dose-intensive cisplatin-based CRTs.

METHODS

We reviewed 155 stage III/IV head and neck squamous cell carcinoma patients with no evidence of distant metastasis treated with one of two CRT regimens from 2000 to 2010 at Greater Baltimore Medical Center. Twice-daily radiation was provided as a split course over a 45-day period. Regimen A consisted of concomitant cisplatin (30 mg/m2/1 h) weekly for 6 cycles; regimen B consisted of concomitant cisplatin (12 mg/m2/1 h) and 5-fluorouracil (600 mg/m2/20 h) on days 1 through 5 and days 29 through 33. Main outcome measures included acute toxicities (myelosuppression, neurotoxicity, nephrotoxicity, gastrointestinal dysfunction), unplanned hospitalizations, and disease control at 12 months.

RESULTS

Patients on regimen A were much less likely to experience ototoxicity due to their treatment (0% vs. 9.8%, P = 0.04). They were more likely to experience thrombocytopenia acutely (46% vs. 26%, P = 0.02), but the toxicity was not limiting (grade 1–2). No significant differences exist in the incidence of other toxicities or unplanned hospitalizations. At 1 year, 97% of patients on A vs. 86% of patients on regimen B were free of disease (P = 0.11).

CONCLUSIONS

With concurrent radiotherapy, low-dose, single-agent, weekly cisplatin is less likely than higher-dose daily cisplatin plus 5-fluorouracil provided at the beginning and end of treatment to be associated with ototoxicity. The preliminary data suggest at least equivalent efficacy, but longer follow-up is required.

Quantification of the effect of treatment duration on local-regional failure after definitive concurrent chemotherapy and intensity-modulated radiation therapy for squamous cell carcinoma of the head and neck

BACKGROUND

The purpose of this study was to quantify the effect of treatment duration on locoregional progression after definitive concurrent chemoradiation (CCRT) for squamous cell carcinoma of the head and neck (SCCHN).

METHODS

We conducted a retrospective chart review of patients treated between 2004 and 2010. After a prior analysis, measures were taken to limit therapy beyond 7 weeks. Comparison of outcomes were made between cohorts 1 (2004-2007, n = 78) and 2 (2007-2010, n = 62).

RESULTS

Median therapy duration was statistically significantly different between cohorts as follows: 51 days, cohort 1 and 46 days, cohort 2 (p < .01). Locoregional progression in cohorts 1 and 2 was 19% and 5% (p = .01), respectively. On multivariate analysis, patients with prolonged treatment (≥57 days) had an 8-fold increase in risk of locoregional progression compared to patients who completed on time (p < .01).

CONCLUSION

Treatment duration was a significant predictor of locoregional progression in patients with SCCHN who received definitive CCRT.

Ionizing radiation: the good, the bad, and the ugly

Skin changes caused by ionizing radiation have been scientifically documented since 1902. Ionizing radiation is a widely accepted form of treatment for various types of cancer. Despite the technological advances, radiation skin injury remains a significant problem. This injury, often referred to as radiation dermatitis, occurs in about 95% of patients receiving radiation therapy for cancer, and ranges in severity from mild erythema to moist desquamation and ulceration. Ionizing radiation is not only a concern for cancer patients, but also a public health concern because of the potential for and reality of a nuclear and/or radiological event. Recently, the United States has increased efforts to develop medical countermeasures to protect against radiation toxicities from acts of bioterrorism, as well as cancer treatment. Management of radiation dermatitis would improve the therapeutic benefit of radiation therapy for cancer and potentially the mortality expected in any "dirty bomb" attack. Currently, there is no effective treatment to prevent or mitigate radiation skin injury. This review summarizes "the good, the bad, and the ugly" of current and evolving knowledge regarding mechanisms of and treatments for radiation skin injury.

Effect of delaying surgery on radical prostatectomy outcomes: a contemporary analysis

Study Type - Therapy (case series). Level of Evidence 4. What's known on the subject? and What does the study add? For patients electing surgical treatment, the question of the effect of surgical delay on clinical outcomes in prostate cancer is controversial. In this study we examined the effect of delay from diagnosis to surgery on outcomes in men with localized prostate cancer and found no association between time to surgery and risk of biochemical recurrence, even for patients with longer delays and high-risk disease. Men with localized prostate cancer can be reassured that reasonable delays in treatment will not influence disease outcomes.

OBJECTIVE

• To examine the effect of time from last positive biopsy to surgery on clinical outcomes in men with localized prostate cancer undergoing radical prostatectomy (RP).

PATIENTS AND METHODS

• We conducted a retrospective review of 2739 men who underwent RP between 1990 and 2009 at our institution. • Clinical and pathological features were compared between men undergoing RP ≤ 60, 61-90 and >90 days from the time of prostate biopsy. • A Cox proportional hazards model was used to analyse the association between clinical features and surgical delay with biochemical progression. Biochemical recurrence (BCR)-free rates were assessed using the Kaplan-Meier method.

RESULTS

• Of the 1568 men meeting the inclusion criteria, 1098 (70%), 303 (19.3%) and 167 (10.7%) had a delay of ≤ 60, 61-90 and >90 days, respectively, between biopsy and RP. A delay of >60 days was not associated with adverse pathological findings at surgery. • The 5-year survival rate was similar among the three groups (78-85%, P= 0.11). • In a multivariate Cox model, men with higher PSA levels, clinical stages, Gleason sums, and those of African-American race were all at higher risk for developing BCR. • A delay to surgery of >60 days was not associated with worse biochemical outcomes in a univariate and multivariate model.

CONCLUSIONS

• A delay of >60 days is not associated with adverse pathological outcomes in men with localized prostate cancer, nor does it correlate with worse BCR-free survival. • Patients can be assured that delaying treatment while considering therapeutic options will not adversely affect their outcomes.

A specific approach for elderly patients with head and neck cancer

Approximately 10% of head and neck (HN) tumors occur in patients aged more than or equal to 80 years. In this population, the main challenge for physicians is to deal with the benefit/risk ratio of treatments and tumor-related symptoms. As elderly patients are generally excluded from clinical trials, there is a lack of evidence-based data with regard to the most appropriate multidisciplinary management. The prevalence of frailty and the pattern of comorbidities in this specific population are still unknown. The management of these tumors in a geriatric context is complex due to the high risk of toxicity of locoregional treatments. Thus, physicians often have to adapt to the treatment schedule to decrease potential adverse effects even with a risk of undertreatment. A retrospective series reported that the treatment delivered to elderly patients presenting with HN tumor complies with an institution's policy in less than 50% of cases, emphasizing the need to assess the outcome of personalized/adapted treatment in geriatric patients. The major issue is to determine which adaptation could be carried out, and then, what could be the respective individual benefit/risk ratio of each adaptation. In this review, we will focus on the locoregional management of elderly patients, and develop the issue of adapted local treatment. We will discuss the feasibility of adapted surgery and radiotherapy and provide current evidence-based data that may allow physicians involved in locoregional treatment of elderly patients with HN cancers to be acquainted with practical guidelines. Then, we will highlight the importance of nutritional support in this population in which the prevalence of malnutrition is high.

Stereotactic body radiation therapy in non-small-cell lung cancer: linking radiobiological modeling and clinical outcome

For patients with peripheral, early-stage non-small-cell lung cancer, it has been found feasible to deliver 5 or fewer fractions of large doses through stereotactic body radiation therapy (SBRT) without causing severe early or late injury and with impressive tumor control. In this review, we employ radiobiological modeling with the linear quadratic formulation to explore the adequacy of various dose schedules used for tumor control in the lung as supported by clinical evidence, the influence of dose distribution and delivery time on local control, and how to decrease the likelihood of severe toxicity following SBRT. Furthermore, the validity of the linear quadratic formalism in the high dose range of SBRT for lung cancer is explored.

Treatment Interruptions in Radiation Therapy for Head-and-Neck Cancer: Rates and Causes

BACKGROUND AND PURPOSE

Extending the period over which a course of radiation therapy is delivered can have detrimental effects on treatment success. This is especially true for fast growing tumors of the head-and-neck region. The goal of this study was to establish the rates and causes of treatment interruptions for head-and-neck patients at the Vancouver Cancer Centre of the BC Cancer Agency, and to explore the link between emotional distress and missed appointments.

METHODS

Head-and-neck patients who had missed treatments other than public holidays were identified using the Oncology Reporting System. The charts of these patients were pulled and examined for cause of treatment interruption. The Psychosocial Screen for Cancer (PSSCAN) found in these patients' charts was used to establish anxiety and depression levels. A random sample of PSSCANs from the charts of patients who had not missed appointments was recorded for comparison.

RESULTS

Of the 471 head-and-neck patients included in our analysis, 74% had interruptions in treatment. Gaps of greater than three days were present in 11% of treatment courses. The most common cause of treatment breaks was statutory holidays, responsible for 69% of interruptions. The anxiety and depression scores of patients who had missed appointments for reasons other than holidays were not significantly higher than patients who had not missed appointments.

CONCLUSION

Rates of treatment time extension in Vancouver were higher than expected, given rates reported from other parts of the world. Policies aimed at reducing or compensating for treatment interruptions have been successful elsewhere, and could also be instituted here. Although many published studies have shown emotional distress can lead to noncompliance in health care, this link was not found here. Several weaknesses in our study design may have contributed to the lack of correlation between anxiety and depression and missed appointments.

Cetuximab in the management of locoregionally advanced head and neck cancer: expanding the treatment options?

The treatment of locoregionally advanced squamous cell carcinoma of the head and neck (SCCHN) has evolved in recent years as a consequence of a better understanding of the potential benefits associated with altered radiation fractionation regimens, concurrently administered chemotherapy and radiotherapy (chemoradiotherapy) and induction chemotherapy. Concurrent chemoradiotherapy is a treatment option for technically resectable disease, where functional morbidity precludes the use of surgery. Induction chemotherapy followed by radiotherapy may also be used in this setting, and has been validated for larynx preservation. Concurrent chemoradiotherapy is a standard treatment approach for medically fit patients with locoregionally advanced unresectable disease. However, the toxicity burden of additional chemotherapy in both the concurrent chemoradiotherapy and induction chemotherapy settings can have implications for treatment compliance and may impede the administration of chemotherapy and/or radiotherapy to schedule. The epidermal growth factor receptor (EGFR)-targeted IgG1 monoclonal antibody, cetuximab (Erbitux), has shown significant clinical benefits in the treatment of both locoregionally advanced and recurrent and/or metastatic SCCHN. A phase III study in locoregionally advanced disease demonstrated significant improvements in locoregional control and progression-free and overall survival with cetuximab plus radiotherapy compared with radiotherapy alone, and overall survival benefits were maintained at 5 years. The addition of cetuximab to concurrent chemoradiotherapy has been shown to be feasible in phase II trials and is being investigated in phase III trials. Preliminary evidence suggests that cetuximab could be incorporated into induction management strategies. Taken together, these data support an important role for cetuximab in the treatment paradigm for locoregionally advanced SCCHN.

The role of the primary care physician during the active treatment phase

Although more research needs to be done to determine the optimal role for PCPs during the active phase of cancer treatment, patients, PCPs, and oncologists all see a significant role for primary care in the care of patients with cancer. In the United States, family physicians are actively involved in the care of cancer patients, especially in provision of support, education, and care of intercurrent illness and chronic disease. Fatigue, depression, pain, and psychosocial distress are important symptoms that should be screened for and addressed. The PCP should be aware of adverse effects of chemotherapy and radiation and cancer-related emergencies. Sexual and intimacy concerns, including contraception and fertility, are important to patients entering active cancer treatment but may not be addressed adequately in usual cancer care. Advising the patient in active cancer treatment on issues of general health including common nutritional issues can provide value through the treatment period. Use of CAM is common and several modalities have been shown to benefit patients in the course of cancer treatment.

Radiation treatment interruptions greater than one week and low hemoglobin levels (12 g/dL) are predictors of local regional failure after definitive concurrent chemotherapy and intensity-modulated radiation therapy for squamous cell carcinoma of the head and neck

PURPOSE

To determine whether baseline hemoglobin level and radiation treatment interruptions predict for loco-regional failure after intensity-modulated radiation therapy (IMRT) with concurrent chemotherapy for definitive treatment of squamous cell carcinoma of the head and neck (SCCHN).

METHODS

This retrospective review identified 78 consecutive patients treated with definitive concurrent chemoradiation for SCCHN. Patients were treated with IMRT to 70 Gy in 35 daily fractions to the high-dose target volume and 56 Gy to the elective target volume.

RESULTS

Median age of the cohort was 62 (37-81). Median follow-up was 12 months. Tumor sites included: oropharynx (54%), larynx (36%), oral cavity (5%), and hypopharynx (5%). Fifteen of 78 patients (19%) experienced loco-regional failure. These included: 6 primary site failures, 5 regional failures, and 4 failures in both the primary site and regional lymph nodes. All but one failure occurred in the high-dose target volume. Only duration of radiation treatment and baseline hemoglobin levels were significant predictors of local control. Loco-regional failure occurred in 6 of 13 patients (46%) with radiation treatment interruptions (>1 week) versus 9 of 65 patients (14%) completing radiation therapy without interruption (P = 0.0148). Loco-regional failure occurred in 7 of 19 patients (37%) whose pretreatment hemoglobin level was <12 g/dL compared with 8 of 59 patients (14%) with hemoglobin levels > or = 12 (P = 0.042).

CONCLUSION

Overall radiation treatment time and pretreatment hemoglobin level were significant predictors for loco-regional failure after definitive concurrent chemotherapy and IMRT for SCCHN.

Radiochemotherapy including cisplatin alone versus cisplatin + 5-fluorouracil for locally advanced unresectable stage IV squamous cell carcinoma of the head and neck

BACKGROUND AND PURPOSE

The optimal radiochemotherapy regimen for advanced head-and-neck cancer is still debated. This nonrandomized study compares two cisplatin-based radiochemotherapy regimens in 128 patients with locally advanced unresectable stage IV squamous cell carcinoma of the head and neck (SCCHN).

PATIENTS AND METHODS

Concurrent chemotherapy consisted of either two courses cisplatin (20 mg/m(2)/d1-5 + 29-33; n = 54) or two courses cisplatin (20 mg/m(2)/d1-5 + 29-33) + 5-fluorouracil (5-FU; 600 mg/m(2)/d1-5 + 29-33; n = 74).

RESULTS

At least one grade 3 toxicity occurred in 25 of 54 patients (46%) receiving cisplatin alone and in 52 of 74 patients (70%) receiving cisplatin + 5-FU. The latter regimen was particularly associated with increased rates of mucositis (p = 0.027) and acute skin toxicity (p = 0.001). Seven of 54 (13%) and 20 of 74 patients (27%) received only one chemotherapy course due to treatment-related acute toxicity. Late toxicity in terms of xerostomia, neck fibrosis, skin toxicity, and lymphedema was not significantly different. The 2-year locoregional control rates were 67% after cisplatin alone and 52% after cisplatin + 5-FU (p = 0.35). The metastases-free survival rates were 79% and 69%, respectively (p = 0.65), and the overall survival rates 70% and 51%, respectively (p = 0.10). On multivariate analysis, outcome was significantly associated with performance status, T-category, N-category, hemoglobin level prior to radiotherapy, and radiotherapy break > 1 week.

CONCLUSION

Two courses of fractionated cisplatin (20 mg/m(2)/day) alone appear preferable, as this regimen resulted in similar outcome and late toxicity as two courses of cisplatin + 5-FU, but in significantly less acute toxicity.

Gap compensation during accelerated hypofractionated radiotherapy in head and neck cancer

Introduction:In squamous-cell carcinoma (SCC) of the head and neck, unplanned gaps risk prolongation of the overall treatment time (OTT) and reduction in tumour control. This audit determines whether further acceleration can safely be employed to compensate for missed treatments during accelerated hypofractionated radiotherapy.

Methods:Patients receiving accelerated hypofractionated radiotherapy for SCC of the head and neck were prospectively audited. Outcome measures were OTT, degree of compensation and acute toxicity determined by incidence of grade 3 mucositis, prolonged grade 3 mucositis, grade 3 dysphagia and pain.

Results:In the 87 patients identified, the dose administered was 55 Gy in 20 fractions (81 patients), 50 Gy in 20 fractions (1 patient) and 50 Gy in 16 fractions (5 patients). Of those patients receiving 20 fractions, 94% completed within 28 days. Grade 3 mucositis was seen in 56 patients (64%). Compensating for unplanned gaps did not result in any significant increase in toxicity. Administering 6 fractions/week, as compensation, was associated with a lower pain score (p= 0.003) as was receiving 2 fractions on the same day (p= 0.0004).

Conclusions:Accelerated hypofractionation is tolerable with most patients completing treatment within the planned OTT. When unplanned gaps occur, then compensation by further acceleration is possible.

Five year results of a randomized trial comparing hyperfractionated to conventional radiotherapy over four weeks in locally advanced head and neck cancer

BACKGROUND AND PURPOSE

Fractionation strategies delivered over 4 weeks are of clinical and radiobiological interest because treatment is completed before radiotherapy (RT) induced clonogen proliferation commences in earnest approximately 3 to 4 weeks into a course of RT. We wished to test the clinical hypothesis that an increased total dose delivered over 4 weeks with smaller than standard doses per fraction in locally advanced squamous cell carcinoma (SCC) may result in relative protection of late responding tissues and an increased tumor control compared to a conventional daily course in the same overall time.

MATERIALS AND METHODS

Between 1988 and 1995 a randomized controlled trial employing RT alone was undertaken at the Princess Margaret Hospital that included 331 eligible patients with T3 or T4 N0 or any N-positive oropharynx, hypopharynx, or larynx primary SCC. RT was randomly assigned to one of two 4 week schedules, either 51 Gy in 20 equal daily fractions, termed conventional fractionation (CF), or 58 Gy in 40 equal fractions given twice per day as a hyperfractionated (HF) experimental arm.

RESULTS

The 5-year local relapse rate was reduced in the HF (41%) compared to the CF arm (49%). This difference was marginally not significant (p=0.082) when the effect was not adjusted. When the effect of the treatment was adjusted by Cox model for clinical factors that included N-category, ECOG performance status, site of disease, T-category, age, hemoglobin, and gender the HF achieved a significant effect (p=0.02). Survival (40% vs. 30%) was also improved with HF compared to CF arm. This difference was only marginally not significant (p=0.069) but again achieved statistical significance when the model was adjusted for clinical factors (p=0.01). Similar results were observed for disease free survival. Although reversible acute toxicity was increased with HF, the overall 5-year rate of grade 3 and 4 late toxicity for the CF was 10.5% compared to 7.7% in the higher dose HF arm.

CONCLUSIONS

HF delivered in 4 weeks permits enhanced RT doses achieving improved tumor control, without increased late toxicity, compared to daily fractionated radiotherapy in the same overall time.

Molecular Biology for the Radiation Oncologist: the 5Rs of Radiobiology meet the Hallmarks of Cancer

Recent advances in our understanding of the biology of cancer have provided enormous opportunities for the development of novel therapies against specific molecular targets. It is likely that most of these targeted therapies will have only modest single agent activities but may have the potential to accentuate the therapeutic effects of ionising radiation. In this introductory review, the 5Rs of classical radiobiology are interpreted in terms of their relationship to the hallmarks of cancer. Future articles will focus on the specific hallmarks of cancer and will highlight the opportunities that exist for designing new combination treatment regimens.

Locally advanced stage IV squamous cell carcinoma of the head and neck: impact of pre-radiotherapy hemoglobin level and interruptions during radiotherapy

PURPOSE

Stage IV head and neck cancer patients carry a poor prognosis. Clear understanding of prognostic factors can help to optimize care for the individual patient. This study investigated 11 potential prognostic factors including pre-radiotherapy hemoglobin level and interruptions during radiotherapy for overall survival (OS), metastases-free survival (MFS), and locoregional control (LC) after radiochemotherapy.

METHODS AND MATERIALS

Eleven factors were investigated in 153 patients receiving radiochemotherapy for Stage IV squamous cell head and neck cancer: age, gender, Karnofsky performance score (KPS), tumor site, grading, T stage, N stage, pre-radiotherapy hemoglobin level, surgery, chemotherapy type, and interruptions during radiotherapy>1 week.

RESULTS

On multivariate analysis, improved OS was associated with KPS 90-100 (relative risk [RR], 2.36; 95% confidence interval [CI], 1.20-4.93; p=.012), hemoglobin>or=12 g/dL (RR, 1.88; 95% CI, 1.01-3.53; p=.048), and no radiotherapy interruptions (RR, 2.59; 95% CI, 1.15-5.78; p=.021). Improved LC was significantly associated with lower T stage (RR, 2.17; 95% CI, 1.16-4.63; p=.013), hemoglobin>or=12 g/dL (RR, 4.12; 95% CI, 1.92-9.09; p<.001), surgery (RR, 2.67; 95% CI, 1.28-5.88; p=.008), and no radiotherapy interruptions (RR, 3.32; 95% CI, 1.26-8.79; p=.015). Improved MFS was associated with KPS 90-100 (RR, 3.41; 95% CI, 1.46-8.85; p=.012).

CONCLUSIONS

Significant predictors for outcome in Stage IV head and neck cancer were performance status, stage, surgery, pre-radiotherapy hemoglobin level, and interruptions during radiotherapy>1 week. It appears important to avoid anemia and radiotherapy interruptions to achieve the best treatment results.

A phase I study of dose-escalated chemoradiation with accelerated intensity modulated radiotherapy in locally advanced head and neck cancer

BACKGROUND AND PURPOSE

Intensity modulated radiotherapy (IMRT) allows the delivery of higher and more homogeneous radiation dose to head and neck tumours. This study aims to determine the safety of dose-escalated chemo-IMRT for larynx preservation in locally advanced head and neck cancer.

METHODS

Patients with T2-4, N1-3, M0 squamous cell carcinoma of the larynx or hypopharynx were treated with a simultaneous-boost IMRT. Two radiation dose levels (DL) were tested: In DL 1, 63 Gy/28F was delivered to primary tumour and involved nodes and 51.8 Gy/28F to elective nodes. In DL 2, the doses were 67.2 Gy/28F and 56 Gy/28F, respectively, representing a 9% dose escalation for the primary. All patients received 2 cycles of neoadjuvant cisplatin and 5-fluorouracil, and concomitant cisplatin. Acute (NCICTCv.2.0) and late toxicity (RTOG and modified LENTSOM) were collected.

RESULTS

Thirty patients were entered, 15 in each dose level. All patients completed the treatment schedule. In DL 1, the incidences of acute G3 toxicities were 27% (pain), 20% (radiation dermatitis), 0% (xerostomia) and 67% required gastrostomy tubes. For DL 2 the corresponding incidences were 40%, 20%, 7%, and 87%. G3 dysphagia and pain persisted longer in DL 2. With regard to mucositis, a prolonged healing time for DL 2 was found, with prevalence of G2 of 58% in week 10. No acute grade 4 toxicity was observed. At 6 months, 1 patient in DL 2 had G3 late toxicity (dysphagia). No dose limiting toxicity was found. Complete response rates were 80% in DL 1, and 87% in DL 2.

CONCLUSION

Moderately accelerated chemo-IMRT is safe and feasible with good compliance and acceptable acute toxicity. Dose escalation was possible without a significant difference in acute toxicity. Longer follow-up is required to determine the incidence of late radiation toxicities, and tumour control rates.

α/β ratio: A dose range dependence study

PURPOSE

To investigate the dependence of the alpha/beta ratio determined from in vitro survival curves on the dose ranges.

METHODS

Detailed clonogenic cell survival experiments were used to determine the least squares estimators for the linear quadratic model for different dose ranges. The cell lines used were CHO AA8, a Chinese hamster fibroblast cell line; U-373 MG, a human glioblastoma cell line; and CP3 and DU-145, two human prostate carcinoma cell lines. The alpha, beta, and alpha/beta ratio behaviors, combined with a goodness-of-fit analysis and Monte Carlo simulation of the experiments, were assessed within different dose regions.

RESULTS

Including data from the low-dose region has a significant influence on the determination of the alpha, beta, and alpha/beta ratio from in vitro survival curve data. In this region, the values are poorly determined and have significant variability. The mid-dose region is characterized by more precise and stable values and is in agreement with the linear quadratic model. The high-dose region shows relatively small statistical error in the fitted parameters but the goodness-of-fit and Monte Carlo analyses showed poor quality fits.

CONCLUSION

The dependence of the fitted alpha and beta on the dose range has an impact on the alpha/beta ratio determined from the survival data. The low-dose region had a significant influence that could be a result of a strong linear, rather than quadratic, component, hypersensitivity, and adaptive responses. This dose dependence should be interpreted as a caution against using inadequate in vitro cell survival data for alpha/beta ratio determination.

Fitting the linear–quadratic model to detailed data sets for different dose ranges

Survival curve behaviour and degree of correspondence between the linear-quadratic (LQ) model and experimental data in an extensive dose range for high dose rates were analysed. Detailed clonogenic assays with irradiation given in 0.5 Gy increments and a total dose range varying from 10.5 to 16 Gy were performed. The cell lines investigated were: CHOAA8 (Chinese hamster fibroblast cells), U373MG (human glioblastoma cells), CP3 and DU145 (human prostate carcinoma cell lines). The analyses were based on chi2-statistics and Monte Carlo simulation of the experiments. A decline of LQ fit quality at very low doses (<2 Gy) is observed. This result can be explained by the hypersensitive effect observed in CHOAA8, U373MG and DU145 data and an adaptive-type response in the CP3 cell line. A clear improvement of the fit is discerned by removing the low dose data points. The fit worsening at high doses also shows that LQ cannot explain this region. This shows that the LQ model fits better the middle dose region of the survival curve. The analysis conducted in our study reveals a dose dependency of the LQ fit in different cell lines.

Does a delay between diagnosis and radical prostatectomy increase the risk of disease recurrence?

BACKGROUND

Men diagnosed with clinically localized prostate carcinoma have several treatment options. The investigation of these options may delay the initiation of definitive therapy. In the current study, the authors evaluated whether time from biopsy to radical prostatectomy (RP) was predictive of postoperative biochemical disease recurrence (BCR).

METHODS

A total of 3149 consecutive patients who underwent RP as their initial treatment for prostate carcinoma within a year of diagnosis were identified. The time between diagnosis and RP was entered as a predictor in a multivariate logistic regression model predicting BCR at 3 years, 5 years, 8 years, and 10 years. The year surgery was performed and the nomogram-predicted probability of recurrence, which incorporates stage of disease, Gleason grade, and prostate-specific antigen (PSA) level, were used as covariates.

RESULTS

The authors found no clear evidence of a significant effect of delay to diagnosis on BCR. For those patients treated within 6 months (96% of the total sample) the odds ratio for each additional month of delay was 1.04, 1.07, 1.08, and 1.02, respectively, for 3-year, 5-year, 8-year, and 10-year BCR-free survival (P>0.2 for all analyses). However, the 95% confidence intervals were wide and included the possibility that even a minor delay in surgery might have a large impact on the probability of BCR.

CONCLUSIONS

The time between biopsy and surgery does not appear to have a large effect on the risk of disease recurrence. Counseling patients on the importance of avoiding undue delay to surgery must be based on clinical judgment, particularly with respect to modifying advice based on the patient's risk.

Does the time from biopsy to surgery affect biochemical recurrence after radical prostatectomy?

OBJECTIVE

To evaluate whether the time from biopsy to radical prostatectomy (RP) predicts the biochemical recurrence (BCR) after RP, as men diagnosed with clinically localized prostate cancer have several available treatment options and investigating these alternatives may delay the initiation of definitive therapy.

PATIENTS AND METHODS

We identified 3969 consecutive patients who had RP for clinically localized prostate cancer from 1987 to 2002; those eligible for the study had RP within a year of diagnosis. The interval between biopsy and RP was analysed both as a continuous and as a dichotomous variable (divided at 3 months). Multivariate analysis was used to evaluate the impact of time to RP on BCR. Subsets were also analysed for the effect of time to RP in patients considered to be at high risk of recurrence, with group 1 having a prostate specific antigen (PSA) level of > or = 20 ng/mL, a biopsy Gleason score of > or = 8, or clinical stage > or = T2c; and group 2 assessed as having a >40% probability of BCR using a preoperative nomogram.

RESULTS

In all, 3149 patients met the inclusion criteria and had a mean (interquartile range) follow-up after RP of 5.4 (2.2-7.9) years. Multivariate analysis showed that the year of biopsy, PSA level before biopsy, clinical stage and biopsy Gleason score (all P < 0.001) were significantly associated with BCR after RP. The time to RP, treated either as a continuous variable (P = 0.252) or when categorized at 3 months (P = 0.939), failed to predict BCR. Further, the time to RP was not an independent predictor of BCR for patients at high risk of recurrence in group 1 (P = 0.147) or group 2 (P = 0.548).

CONCLUSIONS

The time from biopsy to RP did not influence the probability of BCR for men who had RP within a year of diagnosis, even for those considered to be at high risk of BCR. Instead, the clinical and pathological features of the cancer provided the best estimate of the risk of BCR.

The Effect of Treatment Interruptions in the Postoperative Irradiation of Breast Cancer

OBJECTIVE

There is much evidence for the detrimental effect of treatment interruptions on tumor control, particularly in head and neck cancer. In order to determine the outcome of the treatment interruptions in postoperative irradiation of breast cancer, 853 female patients treated between 1990 and 1999 inclusive were retrospectively analyzed.

METHODS

Locally advanced breast cancer patients who received neoadjuvant chemotherapy were not included in the study. Five hundred and forty-six patients (64%) treated with mastectomy and 307 patients (36%) with breast-conserving surgery were analyzed. A total dose of 50 Gy (46--54 Gy) was given to the chest wall/breast and regional lymph nodes in 1.8- to 2-Gy daily fractions, 5 times per week. A 14-Gy (10- to 20-Gy) photon or electron boost was given to the tumor bed of the patients with breast-conserving surgery. Unplanned treatment interruptions occurred in 741 (87%) of the patients and the median duration of the gaps was 13 days (1--91 days). A total of 348 patients (41%) had no treatment break or interruptions of 1 week or less, whereas 505 patients (59%) had treatment interruptions of more than 1 week. The locoregional control (LC) and overall survival (OS) rates were estimated with the Kaplan-Meier method. A Cox proportional hazard regression model was used to evaluate the influence of host- and treatment-related factors on LC and OS (age, menopausal status, histological subtype, grade, hormonal receptor status, pT stage, pN stage, type of surgery, adjuvant treatment, number of gaps and duration of gaps).

RESULTS

For all patients LC rates for 5 and 10 years were 95 and 87%, respectively, and OS rates were 78% for 5 years and 62% for 10 years. LC rates for the group of patients with no treatment break or interruptions of 1 week or less, for 5 and 10 years were 94 and 90%, whereas the LC rates for 5 and 10 years were 89 and 86%, for the group of patients with interruptions of more than 1 week (p=0.019). Treatment interruptions of more than 1 week and premenopausal status appeared to be independent adverse prognostic factors in multivariate analyses affecting the LC (p=0.043 and p=0.005, respectively). The OS rates for the patients without treatment interruptions or interruptions of 1 week or less were also significantly better than for the patients with treatment interruptions of more than 1 week (p=0.026) in multivariate analyses.

CONCLUSION

Interruptions more than 1 week during postoperative irradiation of breast cancer adversely affect the treatment outcome.

Antiemetic therapy in cancer: an update

Although nausea and vomiting are widely recognised as two of the most distressing symptoms of cytotoxic therapy, there is still concern over the adequate control of these symptoms in the cancer population. Recently updated Antiemetic Consensus Guidelines recommend the prophylactic treatment of all patients at moderate-to-high risk of experiencing nausea and vomiting following chemotherapy and radiotherapy. It is important that these guidelines are fully adhered to; however, when considering which antiemetic regimen is most appropriate in an individual patient, it is also important to consider individual patient-related factors. In addition, certain patient groups, such as the young or the elderly, may be in need of specific consideration due to age-related factors that may influence treatment decisions.

Effective health care: management of head and neck cancers

The management of head and neck cancer, published in a recent issue of Effective Health Care, is reviewed.

Prophylaxis versus treatment: is there a better way to manage radiotherapy-induced nausea and vomiting?

Nausea and vomiting are two of the most distressing side effects of radiotherapy and cytotoxic drugs, which currently are often combined to treat moderately advanced and advanced solid tumors. Inadequate control of these symptoms may result in significant patient suffering and decrease in the patient's quality of life, which has been shown to decrease patients' compliance to treatment, with potential impact on disease outcome. It is, therefore, important that radiation oncologists recognize the need for adequate prophylactic treatment of radiation-induced nausea and vomiting (RINV) to avoid the detrimental effects on patients' quality of life, and optimize chances for cure. The 5-hydroxytryptamine type 3 (5-HT(3))-receptor antagonists have been proved to provide effective antiemetic therapy in patients undergoing highly emetogenic radiotherapy. Nevertheless, several large surveys have shown that optimal treatments are not always used. Hence, a risk exists that waiting for RINV symptoms rather than prescribing prophylactic antiemetic treatment may lead to increased patient suffering, poorer disease control, and less cost-effective therapy options. Prophylactic management with an effective 5-HT(3)-receptor antagonist should offer a better treatment option for patients at high to moderate risk of RINV. Adequate control of RINV should contribute to patient compliance to treatment, improved therapy outcomes, and decreased burdens on nursing and health care resources.

Phase III Randomized Trial of Calendula Officinalis Compared With Trolamine for the Prevention of Acute Dermatitis During Irradiation for Breast Cancer

Purpose

The effectiveness of nonsteroid topical agents for the prevention of acute dermatitis during adjuvant radiotherapy for breast carcinoma has not been demonstrated. The goal of this study was to compare the effectiveness of calendula (Pommade au Calendula par Digestion; Boiron Ltd, Levallois-Perret, France) with that of trolamine (Biafine; Genmedix Ltd, France), which is considered in many institutions to be the reference topical agent.

Patients and Methods

Between July 1999 and June 2001, 254 patients who had been operated on for breast cancer and who were to receive postoperative radiation therapy were randomly allocated to application of either trolamine (128 patients) or calendula (126 patients) on the irradiated fields after each session. The primary end point was the occurrence of acute dermatitis of grade 2 or higher. Prognostic factors, including treatment modalities and patient characteristics, were also investigated. Secondary end points were the occurrence of pain, the quantity of topical agent used, and patient satisfaction.

Results

The occurrence of acute dermatitis of grade 2 or higher was significantly lower (41% v 63%; P < .001) with the use of calendula than with trolamine. Moreover, patients receiving calendula had less frequent interruption of radiotherapy and significantly reduced radiation-induced pain. Calendula was considered to be more difficult to apply, but self-assessed satisfaction was greater. Body mass index and adjuvant chemotherapy before radiotherapy after lumpectomy were significant prognostic factors for acute dermatitis.

Conclusion

Calendula is highly effective for the prevention of acute dermatitis of grade 2 or higher and should be proposed for patients undergoing postoperative irradiation for breast cancer.

Three weeks radiotherapy for T1 glottic cancer: the Christie and Royal Marsden Hospital Experience

BACKGROUND AND PURPOSE

Radiotherapy for laryngeal carcinoma is conventionally given over a 6-7-week period. However, in a number of UK centres early lesions are treated over 3 weeks. We review recent results of this policy and discuss the reasons why short treatment times may be advantageous.

MATERIALS AND METHODS

Two hundred patients (100 from each centre) with T1 glottic invasive squamous cell carcinoma treated with definitive radiotherapy between 1989 and 1997 were analysed. The median age was 68 years. All patients received once daily fractionation, 5 days a week to a total tumour dose of 50.0-52.5 Gy in 16 fractions over 21 days; the fraction size ranged from 3.12 to 3.28 Gy. The median follow-up period was 5 years and 10 months.

RESULTS

The 5-year local control rates with radiotherapy for the whole group was 93%; there were 14 recurrences of which seven were salvaged by laryngectomy giving an ultimate local control of 96%. The 5-year overall survival was 80% and cause specific survival at 5 years was 97%. Univariate analysis revealed that T1 substaging (P=0.82) and anterior commissure involvement (P=0.47) did not significantly influence local control. A severe late radiation complication was seen in only one patient who continued to smoke heavily after treatment. There were no severe acute complications.

CONCLUSIONS

Once daily radiotherapy over 3 weeks gives excellent local control in patients with T1 glottic squamous-cell carcinoma and has a low rate of severe complications. The short overall treatment time and large fraction size may be advantageous in radiotherapy of these well-differentiated tumours.

A national audit of radiotherapy in head and neck cancer

AIMS

To undertake a national audit of radiotherapy practice in head and neck cancer to estimate compliance with published guidelines and national standards.

METHODS

A two-part electronic data entry form was distributed to all U.K. radiotherapy centres in September 2000. The first part examined the centres' policies for managing interruptions, the second collected summaries of the management of 50 consecutive patients treated in each centre for head and neck cancer. The outcome measures were: frequency and causes of interruptions to therapy: policy and compliance with policy for managing interruptions; prolongation; and time between first visit to clinic and start of treatment.

RESULTS

Fifty-five out of 56 centres returned data on a total of 2553 patients. Overall, 1467 (55%) patients had one or more treatment interruptions. Of patients whose treatment was interrupted, 56% still completed on time due to compensatory steps, but in 32% no attempted compensation was undertaken. Seven centres had no policy for dealing with treatment interruptions. Centres whose policies included treatment on bank (public) holidays achieved higher compliance and fewer prolonged cases than those whose policies did not. Average time from first visit to head and neck oncology clinic to starting radiotherapy was 40 days; six centres had an average wait of less than 28 days.

CONCLUSIONS

This audit demonstrates wide variations in the quality of care between centres, failure to comply with guidelines for compensation for gaps and failure to meet national targets (for waiting times) that have serious implications both for patient outcomes and for the success of the National Cancer Plan.

Tumor cell repopulation during conventional and accelerated radiotherapy in the in vitro megacolony culture

PURPOSE

To analyze the repopulation rate of cancer cells in vitro during conventional and accelerated irradiation, using the megacolony culture.

MATERIALS AND METHODS

Two cell lines-murine squamous cell carcinoma AT478 and human adenocarcinoma A549-were grown as epithelial megacolonies in vitro, and they were irradiated using Co-60 gamma source at the dose rate of 0.82 Gy/min. Single-dose irradiation, conventional fractionation, and continuous accelerated irradiation (CAIR) were applied to determine the dose-response relationship and to calculate the repopulation balancing dose. Radiosensitivity parameters and the rate of repopulation were calculated from the colony cure rates using direct maximum-likelihood regression and a linear-quadratic model. Cytogenetic radiation damage was measured as frequency of necrotic, apoptototic cells and cells with micronuclei. Mitotic index was used as a simple measure of cell proliferation kinetics.

RESULTS

When treatment time was increased, a significant drop in tumor control probability was detected. The loss of radiation dose calculated from LQ model parameters was equal to 0.8 Gy/day for both human and mouse cell lines. There was no evidence of a lag period for accelerated proliferation or altered proliferation during weekends. There were no significant differences in morphologic presentation of cellular radiation damage.

CONCLUSIONS

In present in vitro experiments, we did not find any significant differences in repopulation or radiosensitivity between accelerated CAIR and conventional fractionation. Different mechanisms may be important for tumor cells repopulation in vitro and in vivo.

Compliance to the prescribed dose and overall treatment time in five randomized clinical trials of altered fractionation in radiotherapy for head-and-neck carcinomas

PURPOSE

To investigate compliance to the prescribed dose-fractionation schedule in five randomized controlled trials of altered fractionation in radiotherapy for head-and-neck carcinoma.

METHODS AND MATERIALS

Individual patient data from 2566 patients participating in the European Organization for Research and Treatment of Cancer (EORTC) 22791, EORTC 22811, EORTC 22851, Princess Margaret Hospital (PMH), and continuous hyperfractionated accelerated radiotherapy (CHART) head-and-neck trials were merged in the fractionation IMPACT (Intergroup Merger of Patient data from Altered or Conventional Treatment schedules) study database. The ideal treatment time was defined as the minimum time required to deliver a prescribed schedule. Compliance to the prescribed overall treatment time was quantified as the difference between the actual and the ideal overall time. An overall measure of compliance in an individual patient, the total dose lost (TDL), was calculated as the dose lost due to prolongation of therapy (assuming a D(prolif) of 0.64 Gy/day) plus the difference between the prescribed and the actual dose given.

RESULTS

The time in excess of the ideal ranged up to 97 days (average 3.9 days), and 25% of the patients had delays of 6 days or more. World Health Organization (WHO) performance status and nodal stage had a significant effect on TDL. TDL was significantly higher in the conventional than in the altered arm of the EORTC 22851 and CHART trials. In the PMH trial, TDL was significantly higher in the hyperfractionation than in the conventional arm. Centers participating in the three EORTC trials varied significantly in their compliance. There was a significant improvement in compliance in patients treated more recently.

CONCLUSIONS

Even in randomized controlled trials, compliance to the prescribed radiation therapy schedule may be relatively poor, especially after conventional fractionation. This affects the interpretation of the outcome of these trials.

Practical methods for compensating for missed treatment days in radiotherapy, with particular reference to head and neck schedules

Unscheduled interruption of a radiotherapy treatment can lead to significant loss in local tumour control, particularly in tumours that repopulate rapidly. General guidelines for dealing with such treatment gaps have been issued by the Royal College of Radiologists and more specific advice on the use of compensation methods has been published previously [Hendry et al., Clin Oncol 1996;8:297-307; Slevin et al., Radiother Oncol 1992;24:215-220]. This article further elaborates on the practical application of these methods. It sets out the main considerations arising in the especially critical case of head and neck treatments and simple calculations are used to illustrate the approaches which may be adapted for particular situations. Radiobiological parameter values are suggested for use in the calculations, but these may require modification in the light of further research in this important area.

Importance of the treatment package time in surgery and postoperative radiation therapy for squamous carcinoma of the head and neck

BACKGROUND

To determine the effect of treatment time-related factors on outcome in patients treated with surgery and postoperative radiation therapy (RT) for locally advanced squamous cell carcinoma of head and neck (SCCHN) METHODS: A retrospective review was performed on 208 consecutive patients treated from 1992 to 1997 with surgery and postoperative RT (> or =55 Gy) for SCCHN. The treatment time factors considered were (1) interval from surgery to the start of RT; (2) RT duration; and (3) the total time from surgery to completion of RT (treatment package time). Treatment package time was dichotomized into short (< or =100 days) vs long (>100 days) categories. Other variables considered were clinical and pathologic staging, margin status, RT dose, and tumor site. Patients were also divided into intermediate- and high-risk groups on the basis of eligibility for RTOG 95-01. Univariate (logrank) and multivariate analyses were performed.

RESULTS

Median follow-up for surviving patients was 24 months. Actuarial 2-year locoregional control (LRC) and survival rates were 82% and 71%, respectively. In univariate analysis, factors associated with higher locoregional failure were high-risk group (p =.011), margin status (p =.038), pathologic stage (p =.035), clinical N stage (p =.006), package time (p =.013), and RT treatment time (p =.03). Package time was also a significant predictor of survival in univariate analysis (p =.021). The other two individual time factors, tumor factors, and RT dose were not significant. Both risk status and treatment package time were significant factors in a multivariate model of LRC.

CONCLUSIONS

A total treatment package time of <100 days is associated with improved tumor control and survival. Every effort should be made to keep the time from surgery to the completion of postoperative RT to <100 days.

Nasopharyngeal cancer WHO type II-III: monoinstitutional retrospective analysis with standard and accelerated hyperfractionated radiation therapy

The aim of this study is to assess the impact of prognostic factors in patients with locoregionally advanced nasopharyngeal cancer (NPC), WHO type II-III, treated with two different radiation therapy (RT) schedules: standard radiation therapy (SRT), and accelerated hyperfractionated radiation therapy (HART), with or without sequential chemotherapy. Between January 1986 and December 1999, 78 consecutive NPC patients were treated either with SRT (until August 1993) or with HART (from September 1993). Of the 78 patients, 60 were males and 18 females, the median age was 56 years (range 14-83). Nine patients had a non-keratinizing carcinoma (WHO type II) and 69 an undifferentiated carcinoma (WHO type III). Five-year overall survival rate (OS) was 62%. Two months after RT, 73 patients were in complete remission. Disease-free survival (DFS) rates at 5 years were: 85% for the HART and 59% for the SRT group, respectively. A multivariate analysis, age (hazard ratio, HR=4.17 for > or = 60 vs. <50 years) and N-stage (HR=3.56 for N3a-N3b vs. N0-N1) were significant for survival, whereas N-stage (HR=8.23 for N3a-N3b vs. N0-N1) and RT schedule (HR=0.30 for HART vs. SRT) were significant for DFS. In our experience, HART achieved higher DFS rates than SRT; however, HART did not favourably affect OS. Toxicity was comparable in the two RT schedules.

T1-T2N0 squamous cell carcinoma of the glottic larynx treated with radiation therapy

PURPOSE

The end results after radiation therapy for T1-T2N0 glottic carcinoma vary considerably. We analyze patient-related and treatment-related parameters that may influence the likelihood of cure.

PATIENTS AND METHODS

Five hundred nineteen patients were treated with radiation therapy and had follow-up for >or= 2 years. Three patients who were disease-free were lost to follow-up at 7 months, 21 months, and 10.5 years. No other patients were lost to follow-up.

RESULTS

Local control rates at 5 years after radiation therapy were as follows: T1A, 94%; T1B, 93%; T2A, 80%; and T2B, 72%. Multivariate analysis of local control revealed that the following parameters significantly influenced this end point: overall treatment time (P < .0001), T stage (P = .0003), and histologic differentiation (P = .013). Patients with poorly differentiated cancers fared less well than those with better differentiated lesions. Rates of local control with laryngeal preservation at 5 years were as follows: T1A and T1B, 95%; T2A, 82%; and T2B, 76%. Cause-specific survival rates at 5 years were as follows: T1A and T1B, 98%; T2A, 95%; and T2B, 90%. One patient with a T1N0 cancer and three patients with T2N0 lesions experienced severe late radiation complications.

CONCLUSION

Radiation therapy cures a high percentage of patients with T1-T2N0 glottic carcinomas and has a low rate of severe complications. The major treatment-related parameter that influences the likelihood of cure is overall treatment time.

No evidence for a different magnitude of the time factor for continuously fractionated irradiation and protocols including gaps in two human squamous cell carcinoma in nude mice

BACKGROUND AND PURPOSE

To study whether the magnitude of the time factor is different for continuously fractionated irradiation and for fractionation protocols including gaps.

MATERIALS AND METHODS

Two human head and neck squamous cell carcinomas (SCCs), FaDu and GL, were transplanted subcutaneously into the right hindleg of NMRI (nu/nu) mice and irradiated with 30 fractions under ambient conditions within 2, 6 and 10 weeks. Irradiations within 6 and 10 weeks were given either as a continuous course or with a mid-course gap of 3 weeks. The end-point of the experiments was local tumor control at day 120 (FaDu) or day 180 (GL) after the end of treatment.

RESULTS

In FaDu tumors, two experimental cohorts (A, B) yielded significantly different results and were analyzed separately. In cohort A, the tumor control dose 50% (TCD50) increased from 37 to 89 Gy when the treatment time of continuous fractionated irradiation was extended from 2 to 10 weeks. The recovered dose/day (D(r)) was 0.98 Gy (95% confidence interval, 0.72; 1.27). In cohort B, the TCD50 increased from 35 to 63 Gy, and the D(r) was 0.51 Gy (0.24; 0.75). In GL tumors, the TCD50 for continuously fractionated irradiation increased from 41 to 48 Gy. This increase was not significant, and the D(r) was 0.15 Gy (0; 0.30). None of the TCD50 and D(r) values obtained in both tumor models for continuous irradiation vs. irradiation with a gap were significantly different.

CONCLUSIONS

Prolongation of the overall treatment time of fractionated irradiation resulted in a pronounced decrease of local control in human FaDu SCC and little decrease of local control in human GL SCC. No evidence was found that the magnitude of the time factor in these tumors is different for continuous fractionation or fractionation protocols including gaps.

Biological aspects of conformal therapy

Both conformal and intensity-modulated radiation therapy have great potential to further increase tumor control rates and decrease morbidity. A homogeneous escalation of 'biological' dose within a tumor should increase the likelihood of local cure, especially within the mid-range (e.g. 15% to 80%) of tumor control rates, and conversely, a lower control rate should follow a homogeneously reduced dose. However, when the dose to critical normal tissues is tightly constrained, the dose distributions within the treatment volume may necessarily be heterogeneous, and the effect on tumor control probability will depend upon the magnitude of over- or underdosage, and on the proportions of the tumor clonogen population receiving higher or lower than the nominal dose. Dose-volume histograms provide a measure of heterogeneity of dose within the planned treatment volume, but tumor control probability is also influenced by other variables, e.g. inherent tumor clonogen radiosensitivity and growth rates during a course of treatment, alpha/beta ratios, oxygenation and clonogen density throughout the target volume. Heterogeneity in these factors introduces heterogeneity in tumor responses and a less steep change in tumor control probability with change in dose, reducing the gains or losses that would be predicted to result from heterogeneity of dose. Similarly, modeling the effect of inhomogeneous dose distributions on estimates of probability of complications in normal tissues is hindered by uncertainty of estimates for alpha/beta ratios, especially for late-responding tissues, and lack of data on volume effects. Although the effects of dose inhomogeneity cannot be presented with sufficiently reliable quantitation to be directly applicable to dose prescriptions in radiation therapy, the relative influences of heterogeneities in dose and volume can be modeled to provide a framework for clinical decision-making. The magnitude of a dose reduction is the major determinant of decline in tumor control probability. A large dose reduction to even a small volume of tumor can profoundly decrease tumor control probability. Conversely, the most rapid improvement in tumor control probability occurs the closer to 100% the amount of tumor exposed to an increased dose. Escalation of dose is of little value unless it is distributed through most of the tumor: even very large increases in dose to small volumes are of little benefit.

Proliferative capacity in head and neck cancer

BACKGROUND

Shortening of overall treatment time (accelerated radiotherapy) appears to result in an increase of the efficacy of irradiation. In this study, we compared the proliferative capacity between tumors originating in different sites of the head and neck region. Tumors with a large proliferating capacity might, theoretically, benefit most from accelerated radiotherapy.

MATERIAL AND METHODS

BrdUrd was administered intravenously in patients with head and neck carcinomas. Tumor samples were analyzed with flow cytometry. T and N stages were assessed in accordance with the TNM classification system (UICC 1987).

RESULTS

No significant differences in proliferation parameters were observed with respect to site of origin of head and neck tumors. For T3/T4 tumors, DNA ploidy is an important tumor characteristic: G1- and S-phase fractions, labeling index, and tumor doubling time Tpot differences were statistically significant; the aneuploid tumors showed the largest proliferative potential.

CONCLUSIONS

(1) In general, no significant differences in proliferation parameters were observed with respect to site of origin. (2) Aneuploid head and neck tumors have a higher proliferative capacity than diploid ones, they might benefit most from accelerated irradiation.

Proliferation parameters in epidermoid carcinomas of the anal canal

PURPOSE

In a prospective study, we assessed the proliferation parameters in primary epidermoid carcinomas of the anal canal, and results were compared with those in cervical carcinomas.

METHODS

Between January 1992 and December 1996, 32 patients with primary epidermoid carcinoma of the anal canal were studied prospectively. Patients were given i.v. bromodeoxyuridine and proliferation parameters were obtained using flow cytometry. The treatment protocol consisted of radiation therapy (XRT) (24 Gy/12-3.5 week split-28 Gy/14) and concurrent 5-fluorouracil and mitomycin C. Proliferation parameters were not obtained in six patients, leaving 26 patients in the analysis. There were 16 females and ten males, with two T1, 16 T2, five T3 and three T4 lesions. Median follow-up was 3.6 years. There were 22 squamous cell and four basaloid carcinomas. Six tumors were aneuploid.

RESULTS

Median values for T(s) and S-phase fraction were 7.7 h and 8.2%, respectively. The median LI was 6.8% (0.9-35.7%), and the median T(pot) was 4.1 days (0.9-30 days). There was no correlation of LI or T(pot) with gender, age, tumor stage, size or histology. Local failure was observed in five patients (T(pot)>4.1 days, n=3; LI>6.8%, n=4). Isolated regional failure or distant disease in the absence of local failure was not observed. The small number of outcome events precluded a definitive analysis of the prognostic role of LI and T(pot). Values for the proliferation parameters were similar to those in our updated study of patients with carcinoma of the uterine cervix (n=107), median LI of 6.7% and median T(pot) of 5.5 days.

CONCLUSIONS

We conclude that proliferation parameters in anal carcinomas are similar to those in cervical carcinomas. Rapid tumor proliferation does not have an apparent adverse impact on outcome in anal carcinomas managed by split-course XRT with concurrent 5-florouracil and mitomycin C.