Afterloading radiotherapy for local persistence of nasopharyngeal carcinoma

Optimal time for early therapeutic response prediction in nasopharyngeal carcinoma with functional magnetic resonance imaging

Background and Purpose

Physiological changes in tumour occur much earlier than morphological changes. They can potentially be used as biomarkers for therapeutic response prediction. This study aimed to investigate the optimal time for early therapeutic response prediction with multi-parametric magnetic resonance imaging (MRI) in patients with nasopharyngeal carcinoma (NPC) receiving concurrent chemo-radiotherapy (CCRT).

Material and Methods

Twenty-seven NPC patients were divided into the responder (N = 23) and the poor-responder (N = 4) groups by their primary tumour post-treatment shrinkages. Single-voxel proton MR spectroscopy (¹H-MRS), diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI were scanned at baseline, weekly during CCRT and post-CCRT. The median choline peak in ¹H-MRS, the median apparent diffusion coefficient (ADC) in DW-MRI, the median influx rate constant (K^trans), reflux rate constant (K_ep), volume of extravascular-extracellular space per unit volume (V_e), and initial area under the time-intensity curve for the first 60 s (iAUC60) in DCE-MRI were compared between the two groups with the Mann-Whitney tests for any significant difference at different time points.

Results

In DW-MRI, the percentage increase in ADC from baseline to week-1 for the responders (median = 11.39%, IQR = 18.13%) was higher than the poor-responders (median = 4.91%, IQR = 7.86%) (p = 0.027). In DCE-MRI, the iAUC60 on week-2 was found significantly higher in the poor-responders (median = 0.398, IQR = 0.051) than the responders (median = 0.192, IQR = 0.111) (p = 0.012). No significant difference was found in median choline peaks in ¹H-MRS at all time points.

Conclusion

Early perfusion and diffusion changes occurred in primary tumours of NPC patients treated with CCRT. The DW-MRI on week-1 and the DCE-MRI on week-2 were the optimal time points for early therapeutic response prediction.

Magnetic Resonance Imaging-Detected Tumor Residue after Intensity-Modulated Radiation Therapy and its Association with Post-Radiation Plasma Epstein-Barr Virus Deoxyribonucleic Acid in Nasopharyngeal Carcinoma

Purpose: To evaluate the prognostic value of magnetic resonance imaging (MRI)-detected tumor residue after intensity-modulated radiation therapy (IMRT) and its association with post-treatment plasma Epstein-Barr virus deoxyribonucleic acid (EBV DNA) in nasopharyngeal carcinoma (NPC).

Methods and materials: A prospective database of patients with histologically-proven NPC was used to retrospectively analyze 664 cases. Pre- and post-treatment MRI scans were independently reviewed by two senior radiologists who were blinded to clinical findings. Factors significantly associated with MRI-detected tumor residue were identified and included in the following multivariate logistic regression model. Residual risk model were established. Receiver operating characteristic (ROC) identify the optimal cut-off risk score for tumor residue.

Results: MRI-detected residual tumor at three months after IMRT was associated with poor prognosis. The 5-year survival rates for the non-residual and residual groups were: OS (93.8% vs. 76.6%, P<0.001), PFS (84.7% vs. 67.9%, P=0.006), LRFS (93.4% vs. 80.4%, P=0.002), and DMFS (90.3% vs. 87.9%, P=0.305), respectively. Three-month post-treatment EBV DNA was significantly associated with tumor residue (P<0.001). A residual risk score model was established, consisting of T and N categories and post-treatment EBV DNA. ROC identified 22.74 as the optimal cut-off risk score for tumor residue. High-risk score was independently associated with poor treatment outcomes.

Conclusions: MRI-detected tumor residue was an independent adverse prognostic factor in NPC; and significantly associated with three-month post-treatment EBV DNA. As limited resources in some endemic areas prevent patients from undergoing routine post-treatment imaging, our study identifies a selection risk-model, providing a cost-effective reference for the selection of follow-up strategies and clinical decision-making.

The effect of adjuvant chemotherapy on survival in patients with residual nasopharyngeal carcinoma after undergoing concurrent chemoradiotherapy

Background

Guidelines from the U.S. National Comprehensive Cancer Network have recommended use of concurrent chemoradiotherapy (CCRT), followed by a 3-cycles combination of platinum and 5-fluorouracil chemotherapy as standard treatment for nasopharyngeal carcinoma (NPC). The benefits of CCRT for treatment of locally advanced NPC have been established. Whether platinum and 5-fluorouracil chemotherapy should be routinely added to locally advanced NPC after CCRT is still open to debate. Whether adjuvant chemotherapy provides an additional survival benefit for the subgroup of patients with residual nasopharyngeal carcinoma who have undergone CCRT is also unclear. This retrospective study was initiated to determine the survival benefit of adjuvant chemotherapy (AC) in residual NPC patients who have undergone concurrent chemoradiotherapy.

Methods

The retrospective study included 155 nasopharyngeal carcinoma patients who had local residual lesions after the platinum-based CCRT without or with AC. Kaplan-Meier analysis and the log-rank test were used to estimate overall survival (OS), failure-free survival (FFS), local relapse-free survival (LRFS) and distant metastasis-free survival (DMFS).

Results

Median follow-up was 47 months. Adjuvant cisplatin or nedaplatin plus 5-fluorouracil chemotherapy did not significantly improve 3-year OS, LRFS, FFS, and DMFS for patients with residual nasopharyngeal carcinoma after undergoing CCRT. The 3-year OS rates for the no-AC group and AC group were 71.6% and 73.7%, respectively (P= 0.44). The 3-year FFS rates for no-AC group and AC group were 57.5% and 66.9%, respectively ((P= 0.19). The 3-year LRFS rates for no-AC group and AC group were 84.7% and 87.9%, respectively ((P= 0.51). The 3-year DMFS rates for no-AC group and AC group were 71.4% and 77.4%, respectively ((P= 0.23).

Conclusions

Since we did not find sufficient data to support significant survival in 3-year OS, LRFS, FFS, and DMFS, whether Adjuvant cisplatin or nedaplatin and 5-fluorouracil chemotherapy should be routinely added to residual nasopharyngeal carcinoma patients after undergoing CCRT remain uncertain.

Current treatment options for local residual nasopharyngeal carcinoma

OPINION STATEMENT

Local residual disease occurs in 7-13 % after primary treatment for nasopharyngeal carcinoma (NPC). To prevent tumor progression and/or distant metastasis, treatment is indicated. Biopsy is the "gold standard" for diagnosing residual disease. Because late histological regression frequently is seen after primary treatment for NPC, biopsy should be performed when imaging or endoscopy is suspicious at 10 weeks. Different modalities can be used in the treatment of local residual disease. Interestingly, the treatment of residual disease has better outcomes than treatment of recurrent disease. For early-stage disease (rT1-2), treatment results and survival rates are very good and comparable to patients who had a complete response after the first treatment. Surgery (endoscopic or open), brachytherapy (interstitial or intracavitary), external or stereotactic beam radiotherapy, or photodynamic therapy all have very good and comparable response rates. Choice should depend on the extension of disease, feasibility of the treatment, and doctor's and patient's preferences and experience, as well as the risks of the adverse events. For the more extended tumors, choice of treatment is more difficult, because complete response rates are poorer and severe side effects are not uncommon. The results of external beam reirradiation and stereotactic radiotherapy are better than brachytherapy for T3-4 tumors. Photodynamic therapy resulted in good palliative responses in a few patients with extensive disease. Also, chemotherapeutics or the Epstein-Barr virus targeted therapies can be used when curative intent treatment is not feasible anymore. However, their advantage in isolated local failure has not been well described yet. Because residual disease often is a problem in countries with a high incidence of NPC and limited radiotherapeutic and surgical facilities, it should be understood that most of the above mentioned therapeutic modalities (radiotherapy and surgery) will not be readily available. More research with controlled, randomized trials are needed to find realistic treatment options for residual disease.

Detection of local failures after management of nasopharyngeal carcinoma: a prospective, controlled trial

OBJECTIVES

To conduct a prospective study (1) to evaluate and compare the efficacies of nasopharyngeal endoscopy and computed tomography in the diagnosis of local failure of external beam radiotherapy for nasopharyngeal carcinoma, and (2) to assess whether multiple endoscopic nasopharyngeal biopsies are superior to a single, targeted biopsy, for the same purpose.

METHODS

Forty-six patients who had been treated with external beam radiotherapy for primary nasopharyngeal carcinoma were enrolled in the study. For every patient recruited, computed tomography, rigid nasopharyngeal endoscopy and nasopharyngeal biopsies were performed 12 weeks after radiotherapy.

RESULTS

Twelve weeks after treatment, six patients (13 per cent) had evident disease on histological examination of biopsies. Nasopharyngeal endoscopy showed a sensitivity, specificity, positive predictive value and negative predictive value of 66.6, 95, 66.6 and 95 per cent, respectively. There was statistically significant agreement between the endoscopic findings and the histological findings (Kappa reliability coefficient = 0.617, p < 0.01). Computed tomography showed a sensitivity, specificity, positive predictive value and negative predictive value of 50, 45, 12 and 85.7 per cent, respectively. There was no statistically significant agreement between the computed tomography findings and the histological findings (Kappa reliability coefficient = 0.021, p > 0.05). A targeted, single biopsy performed under endoscopic control demonstrated excellent sensitivity, specificity, positive predictive value and negative predictive value, being 83.3, 100, 100 and 97.5 per cent, respectively. The Kappa test showed a very statistically significant agreement between the histological findings for the single and the multiple endoscopic biopsies (Kappa reliability coefficient = 0.897, p < 0.001).

CONCLUSIONS

Rigid nasopharyngeal endoscopy should be considered the primary follow-up tool after radiotherapy treatment of nasopharyngeal carcinoma, with computed tomography being reserved for patients with histological or symptomatic indications. Routine postnasal biopsies are not necessary, given the excellent specificity and negative predictive value of rigid nasopharyngeal endoscopy. Single, targeted endoscopic biopsy provides an excellent alternative to the usual multiple biopsies. In addition, it reduces cost, time, morbidity and patient discomfort.

Outcome of Fractionated Stereotactic Radiotherapy for 90 Patients With Locally Persistent and Recurrent Nasopharyngeal Carcinoma

PURPOSE

Local recurrence remains one of the major causes of failure in nasopharyngeal carcinoma (NPC). Stereotactic radiosurgery and fractionated stereotactic radiation therapy (FSRT) have recently evolved as a salvage option of NPC. This study was conducted to review the treatment outcome after FSRT for NPC.

METHODS AND MATERIALS

Between September 1999 and December 2005, 90 patients with persistent (Group 1: n = 34, relapse within 6 months of RT) or recurrent (Group 2: n = 56, relapse beyond 6 months) NPC received FSRT using multiple noncoplanar arcs of 8-MV photon to the target. Median FSRT dose was 18 Gy in three fractions (Group 1) or 48 Gy in six fractions (Group 2). Median follow-up was 20.3 months.

RESULTS

Complete response rate after FSRT was 66% for Group 1 and 63% for Group 2. One-, 2-, and 3-year disease-specific survival (DSS) and progression-free survival (PFS) rates for all patients were 82.6%, 74.8%, 57.5%, and 72.9%, 60.4%, 54.5%, respectively. Three-year local failure-free survival, DSS, and PFS rates were 89.4%, 80.7%, and 72.3% for Group 1, and 75.1%, 45.9%, and 42.9% for Group 2, respectively. Multivariate analysis showed that recurrent disease and large tumor volume were independent factors that predicted poorer DSS and PFS. Seventeen patients developed late complications, including 2 with fatal hemorrhage.

CONCLUSIONS

Our results indicate that FSRT is effective for patients with persistent and recurrent NPC. Compared with reported results of radiosurgery, FSRT provides satisfactory tumor control and survival with a lower risk of complications and it may be a better treatment for local failures of NPC.

Dose–response relationship of nasopharyngeal carcinoma above conventional tumoricidal level: A study by the Hong Kong nasopharyngeal carcinoma study group (HKNPCSG)

BACKGROUND AND PURPOSE

To define the dose-response relationship of nasopharyngeal carcinoma (NPC) above the conventional tumoricidal dose level of 66 Gy when the basic radiotherapy (RT) course was given by the 2D Ho's technique.

PATIENTS AND METHODS

Data from all five regional cancer centers in Hong Kong were pooled for this retrospective study. All patients (n = 2426) were treated with curative-intent RT with or without chemotherapy between 1996 and 2000 with the basic RT course using the Ho's technique. The primary endpoint was local control. The prognostic significance of dose-escalation ('boost') after 66 Gy, T-stage, N-stage, use of chemotherapy, sex and age (< or =40 years vs >40 years) was studied. Both univariate and multivariate analyses were performed.

RESULTS

On multivariate analysis, T-stage (P < 0.01; hazard ratio [HR], 1.58) and optimal boost (P = 0.01; HR, 0.34) were the only significant factors affecting local failure for the whole study population, and for the population of patients treated by radiotherapy alone, but not for patients who also received chemotherapy. The following were independent determinants of local failure for patient groups with different T-stages treated by radiotherapy alone: use of a boost in T1/T2a disease (P = 0.01; HR, 0.33); use of a boost (P < 0.01; HR, 0.60) and age (P = 0.01; HR, 1.02) in T3/T4 tumors. Among patients with T2b tumors treated by radiotherapy alone and given a boost, the use of a 20 Gy-boost gave a lower local failure rate than a 10 Gy-boost. There was no apparent excess mortality attributed to RT complications.

CONCLUSIONS

Within the context of a multi-center retrospective study, dose-escalation above 66 Gy significantly improved local control for T1/T2a and T3/4 tumors when the primary RT course was based on the 2D Ho's technique without additional chemotherapy. 'Boosting' in NPC warrants further investigation. Caution should be taken when boosting is considered because of possible increase in radiation toxicity.

Effectiveness of brachytherapy and fractionated stereotactic radiotherapy boost for persistent nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) with local persistence after primary radiotherapy carries a high risk of treatment failure. We compared the effectiveness of brachytherapy and a fractionated stereotactic radiotherapy (SRT) boost in improving tumor control.

METHODS

We retrospectively reviewed the records of 755 patients with NPC treated from 1994 to 2001. Fifty-two patients (7%) had persistent local disease, but seven of them were unsuitable for radiotherapy boost. Overall, 24 patients received brachytherapy boost at a median dose of 20 Gy, and 21 patients received an SRT boost at a median dose of 15 Gy.

RESULTS

Despite the radiotherapy boost, the overall 3-year local failure-free control rate was still significantly lower for patients with persistent disease than for the rest (71% vs 86%, p < .01). Only the SRT subgroup achieved a local failure-free control rate close to that of the complete responders (82% vs 86%, p = .71).

CONCLUSIONS

SRT boost is more effective in reverting the poor prognostic influence of local persistent disease.

Improved local control with stereotactic radiosurgical boost in patients with nasopharyngeal carcinoma

PURPOSE

Treatment of nasopharyngeal carcinoma using conventional external beam radiotherapy (EBRT) alone is associated with a significant risk of local recurrence. Stereotactic radiosurgery (STR) was used to boost the tumor site after EBRT to improve local control.

METHODS AND MATERIALS

Forty-five nasopharyngeal carcinoma patients received a STR boost after EBRT at Stanford University. Seven had T1, 16 had T2, 4 had T3, and 18 had T4 tumors (1997 American Joint Commission on Cancer staging). Ten had Stage II, 8 had Stage III, and 27 had Stage IV neoplasms. Most patients received 66 Gy of EBRT delivered at 2 Gy/fraction. Thirty-six received concurrent cisplatin-based chemotherapy. STR was delivered to the primary site 4-6 weeks after EBRT in one fraction of 7-15 Gy.

RESULTS

At a medium follow-up of 31 months, no local failures had occurred. The 3-year local control rate was 100%, the freedom from distant metastasis rate was 69%, the progression-free survival rate was 71%, and the overall survival rate was 75%. Univariate and multivariate analyses revealed N stage (favoring N0-N1, p = 0.02, hazard ratio HR 4.2) and World Health Organization histologic type (favoring type III, p = 0.002, HR 13) as significant factors for freedom from distant metastasis. World Health Organization histologic type (p = 0.004, HR 10.5) and age (p = 0.01, HR 1.07/y) were significant factors for survival. Late toxicity included transient cranial nerve weakness in 4, radiation-related retinopathy in 1, and asymptomatic temporal lobe necrosis in 3 patients who originally had intracranial tumor extension.

CONCLUSION

STR boost after EBRT provided excellent local control in nasopharyngeal carcinoma patients. The incidence of late toxicity was acceptable. More effective systemic treatment is needed to achieve improved survival.

Managing nasopharyngeal carcinoma with intracavitary brachytherapy

PURPOSE

At our institution, we have been using intracavitary brachytherapy as a boost in selected cases of both primary and recurrent nasopharyngeal carcinoma. The local control, distant metastasis-free rate, overall survival, and morbidity are presented.

METHODS AND MATERIALS

Between January 1, 1955, and August 2000, 576 patients with a diagnosis of nasopharyngeal carcinoma were seen at the department of radiation oncology, University of California-San Francisco, and 55 patients received intracavitary brachytherapy as one part of their treatment. All patients were treated with megavoltage external beam radiation, including 43 patients treated for initial disease and 12 for recurrence. Brachytherapy was routinely used for early cases of T1 and T2 lesions and selected cases of more advanced lesions, as well as recurrent lesions. The median age was 48 years (range 22-85 years); there were 17 women and 38 men, and 39 patients were ethnic Chinese, 13 were white, and 3 were other races. Stage at treatment (primary and recurrent) was I (n=13), II (n=18), III (n=19), and IV (n=5); 18 patients had concurrent chemotherapy. The brachytherapy applicators used were Rotterdam (n=24), balloon (n=16), ovoid (n=14), and ribbon (n=1). The dose rate was high (n=24), low (n=29), or pulsed (n=2). External beam doses ranged from 54 to 72 Gy for primary disease and 30 to 42 Gy for recurrent disease. Brachytherapy doses ranged from 5 to 7 Gy for high dose rate and 10 to 54 Gy for low dose rate.

RESULTS

With a median follow-up of 36 months in those who were treated for primary carcinoma, the 5-year estimate of local control was 89%, the distant metastasis-free rate was 75%, and the overall survival estimate was 86%. Recurrent patients had a median follow-up of 50 months; the 5-year estimate of local control was 64%, the distant metastasis-free rate was 100%, and the overall survival estimate was 91%. Patients with Stage I or II disease had a longer overall survival compared with those with Stage III or IV (p=0.05). There was a significant difference in the rate of distant metastases due to nodal status (N0 vs. N1-N3, p=0.02) or to overall stage (I/II vs. III/IV, p=0.005).

CONCLUSIONS

Intracavitary boost brachytherapy was found to be effective and well tolerated in selected cases of both primary and recurrent nasopharyngeal carcinoma.

Improved local control for early T-stage nasopharyngeal carcinoma--a tale of two hospitals

PURPOSE

To study the efficacy of intracavitary brachytherapy (ICT) in early T-stage nasopharyngeal carcinoma (NPC).

METHODS AND MATERIALS

All early T-stage (T1 and T2 nasal cavity tumour) NPC treated with a curative intent up to 1996 were analyzed (n=743), 163 from the Prince of Wales Hospital (PWH) and 25 from Tuen Mun Hospital (TMH) were given ICT after radical external radiotherapy (ERT; group A). They were compared with 555 patients treated with ERT alone (group B). The radiotherapy techniques were identical between the two hospitals. The ERT delivered the tumoricidal dose (uncorrected biological equivalent dose (BED)-10, > or = 75 Gy) to the primary tumour, and this did not differ in technique or dosage between the two groups. The ICT delivered a dose of 18-24 Gy in three fractions over 15 days to a point 1 cm perpendicular to the midpoint of the plane of the sources.

RESULTS

The local failure was significantly less (crude rates, 6.9 vs. 13.0%; 5-year actuarial rates, 5.8 vs. 11.7%) and the disease-specific mortality was significantly lower (crude rates, 13.8 vs. 18.9%; 5-year actuarial rates, 12.2 vs. 15.2%) in group A compared with group B. ICT was the only significant independent prognostic factor predictive of fewer local failures. When ICT was excluded from the Cox regression model, the total physical dose or the total BED-10 uncorrected for tumour repopulation became significant in predicting the ultimate local failure rate. The two groups were comparable in the rate of the chronic radiation complications. A significant dose-tumour-control relationship existed, plotting the local failure as a function of the total physical dose or the total BED.

CONCLUSIONS

Supplementing ERT, which delivered the tumoricidal dose (uncorrected BED-10, > or = 75 Gy), with ICT significantly enhanced ultimate local control in early T-stage (T1/T2 nasal infiltration) NPC. A significant dose-tumour-control relationship exists above the conventional tumoricidal dose level.

Brachytherapy for primary and recurrent nasopharyngeal carcinoma: 20 years' experience at Long Beach Memorial

PURPOSE

We evaluated treatment outcomes of patients with mostly locally advanced primary and recurrent cancer of the nasopharynx managed with interstitial and intraluminal brachytherapy.

METHODS AND MATERIALS

This is a retrospective analysis of 56 patients with cancer arising from the nasopharynx treated with interstitial and intracavitary afterloading brachytherapy from 1978 to 1997. Patients were divided into three treatment groups: 15 patients with primary cancer (Group 1), 34 patients with recurrent or persistent disease (Group 2), and 7 patients with cancer in the nasopharynx who had history of previous definitive radiation therapy to the nasopharynx for head and neck cancer (Group 3). Fifty-three percent of patients in Group 1 had 1992 AJCC Stage IV disease, and 49% of patients in Groups 2 and 3 had extensive disease (defined as T3, T4, or parapharyngeal extension). Group 1 received megavoltage radiation to 50-60 Gy followed by a boost to the primary site and neck (in cases of persistent neck disease) with a combination of interstitial and intracavitary brachytherapy (mean dose 33-37 Gy). Five patients received chemotherapy, and 6 patients received hyperthermia. Groups 2 and 3 patients were treated with brachytherapy implants (mean dose 50-58 Gy) without external beam radiation. Twenty-five patients received chemotherapy either before or during radiation, and 21 patients received hyperthermia.

RESULTS

The overall survival at 2, 5, and 10 years for patients in Group 1 was 79%, 61%, and 61%, respectively, and for patients in Groups 2 and 3 combined was 48%, 30%, and 20%, respectively. Cause-specific survival at 2, 5, and 10 years was 87%, 74%, and 74%, respectively, for patients in Group 1; and 82%, 60%, and 60%, respectively, for patients in Groups 2 and 3. Local control at 2, 5, and 10 years was 93%, 93%, and 77%, respectively, for patients in Group 1; and 81%, 59%, and 49%, respectively, for patients in Groups 2 and 3. Control in the neck at 2, 5, and 10 years was achieved in 93%, 93%, and 93% of patients, respectively, in Group 1; and 88%, 81%, and 81%, respectively, for patients in Groups 2 and 3. Disease-free survival was 87%, 74%, and 62%, respectively, for patients in Group 1, and 56%, 41%, and 34%, respectively, for patients in Groups 2 and 3. There were 4 peri-operative deaths. One death (2%) was attributable to the development of late complications. Forty-five percent of patients experienced some form of late complications.

CONCLUSION

Interstitial afterloading brachytherapy can provide effective treatment for nasopharyngeal cancers, especially for locally persistent/recurrent and locally extensive lesions.

Intracavitary brachytherapy significantly enhances local control of early T-stage nasopharyngeal carcinoma: the existence of a dose-tumor-control relationship above conventional tumoricidal dose

PURPOSE

To study the efficacy of intracavitary brachytherapy (ICT) in early T-stage nasopharyngeal carcinoma (NPC).

METHODS AND MATERIALS

All T1 and T2 (nasal infiltration) NPC treated with a curative intent from 1984 to 1996 were analyzed (n = 509). One hundred sixty-three patients were given ICT after radical external radiotherapy (ERT) (Group A). They were compared with 346 patients treated by ERT alone (Group B). The ERT delivered the tumoricidal dose (uncorrected BED-10 > or =75 Gy) to the primary tumor and did not differ between the two groups in technique or dosage. The ICT delivered a dose of 18-24 Gy in 3 fractions over 15 days to a point 1 cm perpendicular to the midpoint of the plane of the sources. ICT was used to treat local persistence diagnosed at 4-6 weeks after ERT (n = 101) or as an adjuvant for the complete responders to ERT (n = 62).

RESULTS

The two groups did not differ in patients' age or sex, rate of distant metastasis, rate of regional failure, overall survival, or the follow-up duration. However, Group A had significantly more T2 lesions and Group B had significantly more advanced N-stages. Local failure was significantly less (crude rates 6.75% vs. 13.0%; 5-year actuarial rates 5.40% vs. 10.3%) and the disease-specific mortality was significantly lower (crude rates 14.1% vs. 21.7%; 5-year actuarial rates 11.9% vs. 16.4%) in Group A compared to Group B. Multivariate analysis showed that the ICT was the only significant prognostic factor predictive for fewer local failures (Cox regression p = 0.0328, risk ratio = 0.49, 95% confidence interval (95% CI) = 0.256-0.957). However, when ICT was excluded from the Cox regression model, the total physical dose or the total BED-10 uncorrected for tumor repopulation during the period of radiotherapy became significant in predicting ultimate local failure rate. The two groups were comparable in the incidence rates of each individual chronic radiation complication and the actuarial cumulative rate of the chronic radiation complications, with the exception of chronic radiation nasopharyngeal ulceration/necrosis which occurred in 10 patients in Group A and 1 patient in Group B. Headache (n = 4) and foul smell (n = 8) consequential to ulceration/necrosis were mild and manageable by conservative means. A significant dose-tumor-control relationship existed when local failure was studied as a function of the total physical dose or the total biological equivalent dose (linear quadratic equation, alpha/beta = 10) uncorrected for tumor repopulation during the time course of the radiotherapy.

CONCLUSIONS

Supplementing ERT which delivered tumoricidal dose (uncorrected BED-10 > or =75 Gy), ICT significantly enhanced ultimate local control and avoided the necessity for morbid salvage treatments in early T-stage (T1/T2 nasal infiltration) NPC. The slight increase in chronic radiation ulceration/necrosis after ICT was acceptable with mild and manageable symptoms. Other late complications were not increased. A significant dose-tumor-control relationship exists above the conventional tumoricidal dose level.

Stereotactic radiosurgical boost following radiotherapy in primary nasopharyngeal carcinoma: impact on local control

PURPOSE

Treatment of patients with nasopharyngeal carcinoma using external beam radiation therapy (EBRT) alone results in significant local recurrence. Although intracavitary brachytherapy can be used as a component of management, it may be inadequate if there is extension of disease to the skull base. To improve local control, stereotactic radiosurgery was used to boost the primary tumor site following fractionated radiotherapy in patients with nasopharyngeal carcinoma.

METHODS AND MATERIALS

Twenty-three consecutive patients were treated with radiosurgery following radiotherapy for nasopharyngeal carcinoma from 10/92 to 5/98. All patients had biopsy confirmation of disease prior to radiation therapy; Stage III disease (1 patient), Stage IV disease (22 patients). Fifteen patients received cisplatinum-based chemotherapy in addition to radiotherapy. Radiosurgery was delivered using a frame-based LINAC as a boost (range 7 to 15 Gy, median 12 Gy) following fractionated radiation therapy (range 64.8 to 70 Gy, median 66 Gy).

RESULTS

All 23 patients (100%) receiving radiosurgery as a boost following fractionated radiation therapy are locally controlled at a mean follow-up of 21 months (range 2 to 64 months). There have been no complications of treatment caused by radiosurgery. However, eight patients (35%) have subsequently developed regional or distant metastases.

CONCLUSIONS

Stereotactic radiosurgical boost following fractionated EBRT provides excellent local control in advanced stage nasopharynx cancer and should be considered for all patients with this disease. The treatment is safe and effective and may be combined with cisplatinum-based chemotherapy.

The time course of histologic remission after treatment of patients with nasopharyngeal carcinoma

BACKGROUND

The objective of this study was to define the time course of histologic remission and to evaluate the prognostic significance of delayed histologic remission of patients with nasopharyngeal carcinoma (NPC).

METHODS

Between 1986-1994, 803 patients underwent serial postradiotherapy nasopharyngeal biopsies. Patients with positive histology underwent repeated biopsies every 2 weeks until the biopsies were found to be negative or, if remission did not occur by the 12th week after radiotherapy, treatment was initiated for persistent disease. Patients with positive histology found after the fifth week but who achieved spontaneous remission before the twelfth week were considered to have delayed histologic remission. Negative histology by the sixth week was considered early histologic remission. The outcome of patients with delayed histologic remission, early histologic remission, and persistent disease were compared.

RESULTS

Six hundred and seventeen patients (76.8%) had negative histology within 12 weeks of the completion of radiotherapy and 55 (6.9%) had persistent disease at Week 12. In 131 patients (16.3%) spontaneous remission was observed in repeat biopsies after initial positive histology. With increasing time after radiotherapy, the incidence of positive histology decreased but more patients were found to have persistent disease. Patients with early and delayed histologic remission had 5-year NPC control rates of 82.4% and 76.8%, respectively (P = 0.35) versus a 40% NPC control rate among patients with persistent disease (P < 0.001). The 5-year survival rates were 75.3%, 79.4%, and 54.2%, respectively, for the 3 groups (P < 0.001).

CONCLUSIONS

A high proportion of early positive histology remitted spontaneously. Delayed histologic remission in NPC patients is not a poor prognostic factor and additional treatment is not necessary. A confirmatory biopsy at 10 weeks is recommended before the initiation of salvage treatment.

A new applicator design for endocavitary brachytherapy of cancer in the nasopharynx

INTRODUCTION

In attempting to improve local tumor control by higher doses of radiation, there has been a resurgence of interest in the implementation of brachytherapy in the management of primary and recurrent cancers of the nasopharynx. Brachytherapy with its steep dose fall-off is of particular interest because of the proximity of critical dose limiting structures. Recent developments in brachytherapy, such as the introduction of pulsed-dose-rate and high-dose-rate computerized afterloaders, have encouraged further evolution of brachytherapy techniques.

MATERIALS AND METHODS

We have designed an inexpensive, re-usable and flexible silicone applicator, tailored to the shape of the soft tissues of the nasopharynx, which can be used with either low-dose-rate brachytherapy or high (pulsed)-dose-rate remote controlled afterloaders.

RESULTS AND CONCLUSIONS

This Rotterdam nasopharynx applicator proved to be easy to introduce, patient friendly and can remain in situ for the duration of the treatment (2-6 days). The design, technique of application and the first consecutive 5 years of clinical experience in using this applicator are presented.

The importance of three-dimensional brachytherapy treatment planning for nasopharyngeal carcinoma

High dose rate (HDR) intracavitary brachytherapy is now more frequently incorporated into treatment programmes for patients with persistent and recurrent nasopharyngeal carcinoma (NPC). However, many centres still employ two-dimensional (2-D) image reconstruction for applicators with a three-dimensional (3-D) orientation. In this study, we introduced the use of a mobile modified Nucletron reconstruction box inside the brachytherapy suite for image reconstruction and quality assurance. Three-dimensional reconstruction of the applicators' configurations proved possible and the dose distributions generated by the 2-D and 3-D image reconstructions could be compared. Thirty-one applications were included in this part of the analysis. The results showed that, based on the 2-D planning method, the reference doses were under-prescribed by 1%-10% in all except one patient, whose dose was over-prescribed by 3%. The evaluated doses to the floor of the sphenoid, which was shown to be significant for subsequent local control, was shown to be underestimated by up to 19% or overestimated by 18%, with an average of 5.9% dose underestimation. With this system, the reliability of the anchoring techniques was verified by posttherapy radiographs. Any catheter displacement of more than 1 mm was counted as a failure. Nine of the 43 verified applications were classified as failures, although six of nine catheter displacements measured < or = 2.5 mm. We recommend the routine use of a modified reconstruction box for 3-D image reconstruction for dose calculation and prescription in the treatment of NPC with HDR intracavitary brachytherapy. Quality assurance programmes should be included as an integral part of any HDR treatment; their importance cannot be overemphasized.

Predicting distant failure in nasopharyngeal cancer

In a prospective study of 78 patients with nasopharyngeal cancer, we examined the prognostic significance of T stage, histology, parapharyngeal involvement, and lymph node dimensions, size, and level concerning distant metastasis. AU patients were treated with radical radiotherapy alone and completed 3 to 7 years of follow-up. In univariate analysis of time to metastasis, there was a significant difference stratifying for T stage (T1 and 2 versus T3 and 4), node dimensions (less than 6 versus more than or equal to 6 cm), neck level (above versus below the thyroid notch), and parapharyngeal involvement, but not for bilaterality of lymphadenopathy. Histology was an important prognostic factor related to distant metastasis since none of the 24 World Health Organization class I cases showed distant metastasis versus 14 (26%) of 54 patients with World Health Organization class II/III carcinoma. A multivariate duration model of time to metastasis within the later histologic group suggested that lymph node dimensions, node level, and T stage were the most important factors related to distant metastases, with the hazard ratios being 3.98, 3.23, and 1.76, respectively. Multivariate analysis within the T3- to T4-stage group showed that node dimension was the only significant variable, with an associated hazard ratio of 4.09. Cases with upper-neck lymphadenopathy and node dimensions of less than 6 cm had a distant metastasis rate of <5%. We conclude that adjuvant chemotherapy for nasopharyngeal cancer is justified in T3- and T4-staged cases with nonkeratinizing or undifferentiated histology and with lymph nodes larger than 6 cm and/or located below the thyroid notch.