Has the influence of treatment duration on local control of carcinoma of the cervix been defined?

Radiobiological considerations in combining doses from external beam radiotherapy and brachytherapy for cervical cancer

The recommended radio-therapeutic treatment for cervix cancer consists of a first phase of external beam radiotherapy (EBRT) plus a second phase of brachytherapy (BT), the combined treatment being delivered within 8 weeks. In order to assess a comprehensive dosimetry of the whole treatment, it is necessary to take into account that these two phases are characterized by different spatial and temporal dosimetric distributions, which complicates the task of the summation of the two contributions, EBRT and BT. Radiobiology allows to tackle this issue pragmatically by means of the LQ model and, in fact, this is the usual tool currently in use for this matter. In this work, we describe the rationale behind the summation of the dosimetric contributions of the two phases of the treatment, EBRT and BT, for cervix cancer, as carried out with the LQ model. Besides, we address, from a radiobiological point of view, several important considerations regarding the use of the LQ model for this task. One of them is the analysis of the effect of the overall treatment time in the result of the global treatment. Another important question considered is related to the fact that the capacity of LQ to predict the treatment outcomes is deteriorated when the dose per fraction of the radiotherapic scheme exceeds 6-10 Gy, which is a typical brachytherapy fractionation. Finally, we analyze the influence of the uncertainty and the variability of the main parameters utilized in the LQ model formulation in the assessment of the global dosimetry.

Impact of treatment time-related factors on prognoses and radiation proctitis after definitive chemoradiotherapy for cervical cancer

This study aimed to investigate the impact of treatment time-related factors on outcomes and radiation proctitis in patients undergoing concurrent chemoradiotherapy (CCRT) for cervical cancer. From September 2001 to December 2012, 146 patients with stage IIB cervical squamous cell carcinoma treated with CCRT were reviewed from a prospective cohort. Patients who received the same dose (45 Gy) of external beam radiation therapy (EBRT) were included in the analysis (n = 125). The same equivalent dose of 2 Gy (EQD2) of high-dose-rate intracavitary brachytherapy (HDR-ICBT) was delivered at either 4 fractions of 6 Gy or 6 fractions of 4.5 Gy. The effects of the overall treatment time (OTT) and interval between EBRT and HDR-ICBT on the cancer-specific survival (CSS), local recurrence (LR), and incidence of proctitis were compared. The treatment time-related factors did not adversely affect the CSS and LR rates. The multivariate analyses did not identify the OTT as an independent factor of CSS (P = 0.839) and LR (P = 0.856). However, OTT ≤56 days (P = 0.026) was identified as the only independent factor of overall proctitis. The 5-year Grade 2 or greater proctitis rates were 14.9% and 0% (P = 0.001) in patients with the EBRT to ICBT interval ≤5 days and >5 days, respectively. To reduce rectal damage without compromising prognosis, the gap between EBRT and HDR-ICBT should exceed 5 days in cervical cancer patients undergoing CCRT. Strictly limiting the OTT to 56 days may result in radiation proctitis without improvements in prognosis.

Effect of tumor dose, volume and overall treatment time on local control after radiochemotherapy including MRI guided brachytherapy of locally advanced cervical cancer

BACKGROUND AND PURPOSE

Currently, there is no consensus on dose prescription in image guided adaptive brachytherapy (IGABT) in locally advanced cervical cancer. The purpose of this study was to provide evidence based recommendations for tumor dose prescription based on results from a multi-center patient series (retroEMBRACE).

MATERIALS AND METHODS

This study analyzed 488 locally advanced cervical cancer patients treated with external beam radiotherapy±chemotherapy combined with IGABT. Brachytherapy contouring and reporting was according to ICRU/GEC-ESTRO recommendations. The Cox Proportional Hazards model was applied to analyze the effect on local control of dose-volume metrics as well as overall treatment time (OTT), dose rate, chemotherapy, and tumor histology.

RESULTS

With a median follow up of 46months, 43 local failures were observed. Dose (D90) to the High Risk Clinical Target Volume (CTV_HR) (p=0.022, HR=0.967 per Gy) was significant for local control, whereas increasing CTV_HR volume (p=0.004, HR=1.017 per cm³), and longer OTT (p=0.004, HR=1.023 per day) were associated with worse local control. Histology (p=0.084), chemotherapy (p=0.49) and dose rate (p=1.00) did not have significant impact on local control. Separate analyses according to stage of disease showed that dose to CTV_HR, residual gross tumor volume (GTV_res), and Intermediate Risk CTV (CTV_IR) has significant impact on local control.

CONCLUSION

CTV_HR dose of ⩾85Gy (D90) delivered in 7weeks provides 3-year local control rates of >94% in limited size CTV_HR (20cm³), >93% in intermediate size (30cm³) and >86% in large size (70cm³) CTV_HR. CTV_IR and GTV_res dose of ⩾60Gy and ⩾95Gy (D98) leads to similar local control. A dose of 5Gy (CTV_HR) is required to compensate an increase of OTT by one week. Increased CTV_HR volume by 10cm³ requires additional 5Gy for equivalent local control.

Which clinical/pathologic factors matter in the era of chemoradiation as treatment for locally advanced cervical carcinoma? Analysis of two Gynecologic Oncology Group (GOG) trials

PURPOSE

To explore clinical/pathologic factors associated with prognosis of patients with locally advanced cervical carcinoma treated with weekly cisplatin and pelvic radiation.

METHODS

We retrospectively reviewed data from 335 women who received weekly cisplatin and radiation while participating in similar arms of two GOG studies (protocols 120 and 165). Progression-free survival (PFS) and overall survival (OS) were evaluated for associations between clinical/pathologic factors and prognosis. Prognosis and selected toxicities were also compared between studies.

RESULTS

Four-year PFS and OS for stage II patients were 64.2% and 68.1%, respectively for those treated on GOG 120 and 65.8% and 73.9% for those treated on GOG 165, compared to 51.4% and 55.4% for stage III/IV patients respectively treated on GOG 120 and 37.7% and 42.7% respectively for those treated on GOG 165. In multivariate analysis, stage, tumor grade, race and age were independently predictive of PFS and OS (for all, p<0.05). Prolonged (delayed for any cause) radiation was associated with poorer PFS (hazard ratio [HR], 1.98; 95% confidence interval [CI], 1.16-3.38; p=0.012) and OS (HR, 1.88; 95% CI, 1.08-3.26; p=0.024) in GOG 165 but not GOG 120.

CONCLUSIONS

FIGO stage, tumor grade, race and age are prognostic in patients with locally advanced cervical carcinoma treated with concurrent cisplatin and radiation. This exploratory analysis has generated a hypothesis that clinical staging (as per GOG 165) is less sensitive in detecting aortic nodal metastases compared to surgical staging (as per GOG 120) and may be associated with poorer prognosis particularly when radiation is prolonged. Prospective clinical studies are needed to test this hypothesis.

Patterns of brachytherapy practice for patients with carcinoma of the cervix (1996–1999): A Patterns of Care Study

PURPOSE/OBJECTIVE

To analyze the details of brachytherapy practice in patients treated for carcinoma of the cervix in the United States between 1996 and 1999.

METHODS AND MATERIALS

Radiation facilities were selected from a stratified random sample. Patients were randomly selected from lists of eligible patients treated at each facility. A total of 442 patients' records were reviewed in 59 facilities to obtain data about patients' characteristics, evaluation, tumor extent, and treatment. National estimates were made using weights that reflected the relative contribution of each institution and of each patient within the sampled institutions. From our survey we estimate that 16,375 patients were treated in the United States during this study period. Unless otherwise specified, brachytherapy practice was based on the 408 patients who had their brachytherapy or all their treatment at the surveyed facility.

RESULTS

A total of 91.5% of patients underwent brachytherapy at the initial treating institution; 8.5% were referred to a second site for brachytherapy. Forty-two percent of U.S. facilities referred at least some patients to a second facility for brachytherapy. Of U.S. facilities that treated < or =2 eligible patients per year, 61% referred all of their patients to a second facility for brachytherapy or treated with external RT alone; none of the U.S. facilities with larger experience (>2 eligible patients per year) referred all their patients to a second facility for brachytherapy treatment, but 28% referred some patients to an outside facility for brachytherapy. Overall, 94% of patients who completed treatment with curative intent received brachytherapy. Of these patients who had brachytherapy, 77.8%, 13.3%, and 0.9%, respectively, were treated with low-dose-rate (LDR), high-dose-rate (HDR), or a combination of HDR and LDR brachytherapy; 7.9% had interstitial brachytherapy (5.7% LDR and 1.9% HDR, 0.3% mixed). In facilities that treated >2 patients per year, 15.5% and 9.4% of brachytherapy procedures included HDR or interstitial, respectively; in facilities that treated fewer patients, 3.4% had HDR brachytherapy, and only 1.2% had interstitial brachytherapy. Patients treated with LDR intracavitary radiotherapy had one (23.5%), two (74.1%), or three (2.4%) implants. For patients treated with curative intent who completed radiation therapy with LDR intracavitary radiation therapy without hysterectomy, the median brachytherapy dose to Point A was 40.3 Gy, and the median total dose to Point A was 82.9 Gy. Patients were treated with HDR intracavitary radiation therapy using a variety of treatment schedules using 1-2 fractions (7.5%), 3-4 fractions (17.4%), 5-6 fractions (38.5%), 7-9 fractions (33.5%), or 12 fractions (3%). Fraction sizes were <500 cGy (29.5%), 500-<600 (25.2%), 600 (28.1%), >600 (8%), or unknown (9.2%). For patients treated with HDR, the median total dose to Point A (corrected for fraction size using a alpha/beta = 10) was 85.8 Gy (range: 56.2-116.1 Gy). At institutions treating <500 new patients per year, the percentage of patients receiving a brachytherapy dose <40 Gy was significantly higher than at institutions treating > or =500 new patients per year (p < 0.0001). For LDR intracavitary radiation therapy, 5.8% had neither bladder nor rectal doses recorded for any of their implants, whereas in HDR intracavitary radiation therapy, 73.4% had neither bladder nor rectal doses recorded for any of their implants. The median total duration of radiation therapy was identical for patients who had HDR or LDR intracavitary radiation therapy (57 days). For LDR at institutions treating <500 new patients per year, the percentage of patients with treatment duration >56 days was significantly greater than at institutions > or =500 new patients per year (p = 0.002). Of the patients who had LDR intracavitary radiation therapy implants, 65% were treated using tandem and shielded Fletcher-Suit-Delclos colpostats; other patients had mini ovoids (10.9%), cylinders (3.9%), Henschke (3.7%), or other/mixed applicators (16.5%). In contrast, of patients treated with HDR intracavitary radiation therapy, 68.7% had tandem and rings, 18.2% Fletcher-Suit-Delclos ovoids, 7.5% mini ovoids, 2.3% cylinders, and 3.2% other or mixed applicators.

CONCLUSIONS

The median duration of treatment and median Point A dose were very similar for patients treated with HDR or LDR. Patients with HDR were treated using a variety of treatment schedules. Different applicator types were favored for LDR vs. HDR. Of patients treated with HDR, 73.4% had no brachytherapy bladder or rectal doses recorded, suggesting that full dosimetric calculations were performed only for the first fraction in many institutions. Facility size significantly impacted on referral to another institution for brachytherapy, brachytherapy dose, and treatment duration.

Influence of overall treatment time and radiobiological parameters on biologically effective doses in cervical cancer patients treated with radiation therapy alone

The aim of the study was to examine the influence of overall treatment time (OTT) on the value of calculated biological effective doses (BEDs) for different biological variables. These variables were: tumour proliferation rate, different cell radiosensitivity (alpha=0.2, 0.3, and 0.4 /Gy), and different start time for repopulation (Tk=21, 28, and 35 days). Also the influence of age (</= 50 years >), Hb level (</= 116 g/l>), tumor proliferation rate (bromodeoxyuridine labelling index; BrdUrdLI), and DNA ploidy on survival after shorter (</= 60 days) or longer (>60 days) OTT was investigated. The study included 229 patients with cervix carcinoma treated entirely by standard radiotherapy (RT) (external beam RT plus low-medium dose-rate (LDR/MDR) brachytherapy (BT) at the Center of Oncology in Krakow. The linear quadratic equation was used to calculate BED, which is proportional to log cell kill. BEDs 10 (for tumours) were calculated with consideration of OTT for each patient and tumour proliferation rate (standardized potential doubling time; standardized Tpot) based on BrdUrdLI assessed on biopsy material before RT. Median OTT was 90 days (range 30-210). The mean calculated total BED for point A for tumour and 'early reactions' was equal to 103.0 Gy10. The longest median survival time--52 months--was seen for patients treated with OTT </= 60 days. If OTT exceeded 90 days to more than 120 days, loss in BED10 for relatively radiosensitive tumours (alpha=0.3-0.4/Gy and Tk=28 days) was equal to 0.37-0.26 Gy/day. However, for radioresistant tumours (alpha=0.2/Gy) it was 0.6 Gy/day. For fast proliferating tumours (BrdUrdLI >8.8%) BED loss was 1.4 Gy/day and for slowly proliferating tumours (BrdUrdLI </= 8.8%) it was 0.2 Gy/day. Assuming shorter (21 days) or longer (35 days) periods for Tk and relatively radiosensitive tumours similar BED loss of 0.38 Gy/day was observed. Kaplan-Meier analysis revealed that OTT </= 60 days was a significant prognostic factor for overall survival (OS) (p=0.019), disease-free survival (DFS) (p=0.0173), and local control (LC) (p=0.011). BED10 had significant influence on survival (p=0.047). Cox multivariate analysis revealed that for OTT shorter than 60 days the only favourable significant parameters were: age >50 years (p=0.003) and high Hb level (>116 g/l) (p=0.041). For longer treatments (OTT >60 days) the unfavourable parameters were: age </= 50 years (p=0.037), BrdUrdLI </= 8.8% (p=0.003), tumour aneuploidy (p=0.043), and BED10 </= 103 Gy (p=0.017). The examined tumour biological parameters should be taken into account for RT and provide a basis for adjuvant RT.

Neoadjuvant chemotherapy for locally advanced cervical cancer: a systematic review and meta-analysis of individual patient data from 21 randomised trials

Despite the enrollment of more than 3000 women in randomised trials, the benefits and risks of neoadjuvant chemotherapy in the treatment of locally advanced cervical cancer remain uncertain. We carried out a systematic review and meta-analysis of individual patient data to assess the effect of neoadjuvant chemotherapy in two comparisons. In the first comparison, of neoadjuvant chemotherapy followed by radical radiotherapy compared with the same radiotherapy alone, we obtained data from 18 trials and 2074 patients. When all trials were considered together, a high level of statistical heterogeneity suggested that the results could not be combined indiscriminately. A substantial amount of heterogeneity was explained by separate analyses of groups of trials. Trials using chemotherapy cycle lengths of 14 days and shorter (Hazard Ratio (HR))=0.83, 95% Confidence Interval (CI)=0.69-1.00, P=0.046) or cisplatin dose intensities greater than or equal to 25 mg/m2 per week (HR=0.91, 95% CI=0.78-1.05, P=0.20) tended to show an advantage for neoadjuvant chemotherapy on survival. In contrast, trials using cycle lengths longer than 14 days (HR=1.25, 95% CI=1.07-1.46, P=0.005) or cisplatin dose intensities lower than 25mg/m2 per week (HR=1.35, 95% CI=1.11-1.14, P=0.002) tended to show a detrimental effect of neoadjuvant chemotherapy on survival. In the second comparison, of neoadjuvant chemotherapy followed by surgery compared with radical radiotherapy alone, data from 5 trials and 872 patients were obtained. The combined results from all trials (HR=0.65, 95% CI=0.53-0.80, P=0.0004) indicated a highly significant reduction in the risk of death with neoadjuvant chemotherapy, but there were some differences between the trials in their design and results. Despite some unexplained heterogeneity, the timing and dose intensity of cisplatin-based neoadjuvant chemotherapy appears to have an important impact on whether or not it benefits women with locally advanced cervical cancer and warrants further exploration.

Neoadjuvant chemotherapy for locally advanced cervix cancer

BACKGROUND

Despite the enrollment of more than 3000 women in randomised trials, the benefits and risks of neoadjuvant chemotherapy in the treatment of locally advanced cervical cancer remained uncertain.

OBJECTIVES

This systematic review and individual patient data (IPD) meta-analysis aimed to assess the effect of neoadjuvant chemotherapy in two comparisons: (1) neoadjuvant chemotherapy followed by radical radiotherapy compared to the same radiotherapy alone; and (2) neoadjuvant chemotherapy followed by surgery compared to radical radiotherapy alone.

SEARCH STRATEGY

Medline and CancerLit searches were supplemented with information from trial registers and by hand searching relevant meeting proceedings and by discussion with relevant trialists and organisations. These searches have been updated regularly until December 2002.

SELECTION CRITERIA

To be included, trials had to be properly randomised and had to include patients with locally advanced cervical cancer who had received neoadjuvant cytotoxic chemotherapy before radiotherapy or surgery or both treatments. Concurrent chemoradiotherapy trials were not included. The comparisons had to be unconfounded by use of additional agents or interventions. Patient enrollment should have started after 1 January 1975 and be completed by September 2000.

DATA COLLECTION AND ANALYSIS

We collected, validated and re-analysed updated trial data on all randomised patients from all relevant trials. Any queries were resolved and the final database entries verified by the responsible trial investigator, data manager or statistician. Two separate sets of analyses (by intention-to-treat) were carried out according to the treatment comparisons (1 and 2) already described. For all outcomes, we obtained overall pooled hazard ratios using the fixed effect model. To explore the potential impact of trial design, we pre-planned analyses that grouped trials by important aspects of their design that might influence the treatment effect. To investigate the effects of neoadjuvant chemotherapy within pre-specified subgroups of patients stratified logrank analyses were done on the primary endpoint of survival.

MAIN RESULTS

In the first comparison, we obtained data from 18 trials and 2074 patients. When all trials were considered together, a high level of statistical heterogeneity suggested that the results could not be combined indiscriminately. A substantial amount of heterogeneity was explained by separate analyses of groups of trials. Trials using chemotherapy cycle lengths shorter than 14 days (HR = 0.83, 95% CI = 0.69 to 1.00, p = 0.046) or cisplatin dose intensities greater than 25 mg/m2 per week (HR = 0.91, 95% CI = 0.78 to 1.05, p = 0.20) tended to show an advantage for neoadjuvant chemotherapy on survival. In contrast, trials using cycle lengths longer than 14 days (HR = 1.25, 95% CI = 1.07 to 1.46, p = 0.005) or cisplatin dose intensities lower than 25 mg/m2 per week (HR = 1.35, 95% CI = 1.11 to 1.14, p = 0.002) tended to show a detrimental effect of neoadjuvant chemotherapy on survival. In the second comparison, data from 5 trials and 872 patients were obtained. The combined results from all trials (HR = 0.65, 95% CI = 0.53 to 0.80, p = 0.0004) indicated a highly significant reduction in the risk of death with neoadjuvant chemotherapy, but there were some differences between trials in their design and results.

REVIEWERS' CONCLUSIONS

Despite some unexplained heterogeneity, the timing and dose intensity of cisplatin-based neoadjuvant chemotherapy appears to have an important impact on whether or not it benefits women with locally advanced cervical cancer and warrants further exploration.

Concurrent radiation therapy and paclitaxel or docetaxel chemotherapy in high-risk breast cancer

PURPOSE

Evidence supports the inclusion of the taxanes in the treatment of breast cancer. A recent randomized trial has shown a survival advantage to the addition of paclitaxel in the adjuvant treatment of node-positive patients. Several studies have suggested diminished local control if adjuvant radiation is delayed, while in vitro and in vivo studies have demonstrated a benefit of concurrent administration of taxanes with radiation. For these reasons, we began in 1995 to administer radiation therapy concurrently with the taxanes in advanced breast cancer. This retrospective review examines the feasibility of such treatment.

METHODS AND MATERIALS

Forty-four patients were treated with concurrent radiation and either paclitaxel (29 patients) or docetaxel (15 patients). One patient received both paclitaxel and docetaxel. Eighteen patients were treated for recurrent disease, 9 had received prior radiation. Toxicity was assessed by the RTOG scale for acute and late effects.

RESULTS

Concurrent radiation and taxane chemotherapy was well tolerated. Nine patients (20%) experienced Grade 3 acute skin toxicity. This was more likely with docetaxel than paclitaxel (p = 0. 04). Among patients undergoing breast conservation, there were no Grade 3 toxicities. With a median follow-up of 11 months, 1 patient has developed breast fibrosis.

CONCLUSION

Concurrent administration of both paclitaxel and docetaxel with radiation resulted in acceptable toxicity. Overall, the acute skin toxicity seen with docetaxel was more pronounced. However, among patients undergoing breast conservation the taxanes were both well tolerated. Further study is necessary to assess the impact of concurrent treatment on long-term outcome.

A survey on staging and treatment in uterine cervical carcinoma in the Radiotherapy Cooperative Group of the European Organization for Research and Treatment of Cancer

BACKGROUND

The treatment outcome of advanced stage uterine cervical carcinoma remains unsatisfactory. In order to elaborate a novel trial within The Radiotherapy Cooperative Group (RCG) of the European Organization for Research and Treatment of Cancer (EORTC), we conducted a survey in 1997-1998 to determine the variability of pre-treatment assessment and treatment options. The variability of choosing surgery, defined radiation therapy techniques and chemotherapy are investigated, as well as the center's choices of future treatment strategies.

METHODS

Fifty two of 81 RCG centers from the RCG have participated in the survey. As one would expect, there is a large variation in the techniques used for pretreatment evaluation and treatment options. There is no 'standard' for reporting acute and late side effects. Chemotherapy is used neither systematically nor uniformly, and some centers continue to use neadjuvant chemotherapy modalities.

RESULTS

Furthermore, the survey reveals that there is a strong demand for the reduction of overall treatment-time, for clinical investigation of novel combined modality treatment strategies, especially chemo-radiation therapy, and also for the use of new radiation sensitizers.

CONCLUSION

We conclude that a more homogeneous approach to the pretreatment evaluation as well as treatment techniques is required in order to allow adequate quality control in any future trial of the RCG in the EORTC.

Prognostic significance of pretherapeutic and therapeutic factors in patients with advanced cancer of the uterine cervix treated with radical radiotherapy alone

The prognostic importance of various pretherapeutic and therapeutic factors was analysed in a group of 413 cervical cancer patients with stage IIB (183 pts) and IIIB (230 pts) treated with radical radiotherapy, which consisted of external irradiation and intracavitary brachytherapy. Univariate analysis of pretherapeutic factors revealed the prognostic significance of patient age, history of abortion, stage, haemoglobin and hematocrit levels. Five-year overall survival rate in stage IIB patients was 51%, in stage IIIB 40% and the respective rates for local control at each stage were 61%, and 46%. Univariate analysis of therapeutic factors showed that survival and local control rates increased with the dose, but a significant difference was found only in the case of a paracentral (point A) dose. In a multivariate analysis only patient age, abortions, and clinical stage appeared to have a significant and independent impact on survival. Linear regression analysis results indicated that prolongation of treatment time between 33 and 108 days caused a loss of local control of 0.36% per day.

Muscle-invasive bladder cancer treated with external beam radiation: influence of total dose, overall treatment time, and treatment interruption on local control

PURPOSE

To evaluate and eventually quantify a possible influence of tumor proliferation during the external radiation course on local control in muscle invasive bladder cancer.

METHODS AND MATERIALS

The influence of total dose, overall treatment time, and treatment interruption has retrospectively been analyzed in a series of 379 patients with nonmetastasized, muscle-invasive transitional cell carcinoma of the urinary bladder. All patients received external beam radiotherapy at the Netherlands Cancer Institute between 1977 and 1990. Total dose varied between 50 and 75 Gy with a mean of 60.5 Gy and a median of 60.4 Gy. Overall treatment time varied between 20 and 270 days with a mean of 49 days and a median of 41 days. Number of fractions varied between 17 and 36 with a mean of 27 and a median of 26. Two hundred and fourty-four patients had a continuous radiation course, whereas 135 had an intended split course or an unintended treatment interruption. Median follow-up was 22 months for all patients and 82 months for the 30 patients still alive at last follow-up. A stepwise procedure using proportional hazard regression has been used to identify prognostic treatment factors with respect to local recurrence as sole first recurrence.

RESULTS

One hundred and thirty-six patients experienced a local recurrence and 120 of these occurred before regional or distant metastases. The actuarial local control rate was 40.3% at 5 years and 32.3% at 10 years. In a multivariate analysis total dose showed a significant association with local control (p = 0.0039), however in a markedly nonlinear way. In fact only those patients treated with a dose below 57.5 Gy had a significant higher bladder relapse rate, whereas no difference in relapse rate was found among patients treated with doses above 57.5 Gy. This remained the case even after adjustment for overall treatment time and all significant tumor and patient characteristics. The Normalized Tumor Dose (NTD) (alpha/beta = 10) and NTD (alpha/beta = 15) were not significantly related to local control (p = 0.96 and p = 0.053, respectively). Only weak evidence was found for an association between local control and overall treatment time (p = 0.067). No difference in bladder relapse rate was found among patients treated with a continuous course and patients who had treatment interruptions (p = 0.099). Neither the length of the interruption, nor the actual number of treatment days has a significant influence on local control (p = 0.04 and p = 0.09, respectively).

CONCLUSION

In contrast to two earlier, but smaller reports, in this study no significant effect of treatment prolongation on outcome after radiotherapy could be demonstrated and thus no support was found for an important role for tumor proliferation as the cause of treatment failure in muscle-invasive bladder cancer. Results of large-sized phase III trials will have to be awaited to show any benefit from reduction of the overall treatment time and to quantify the potential effect of tumor proliferation.