Clinical application of intensity-modulated radiotherapy for head and neck cancer

Intensity-modulated radiotherapy (IMRT) is a modern treatment technique that allows one to shape the dose to the target volume and to reduce the dose delivered to healthy tissue. Over the last decade, IMRT has been implemented for head and neck cancer treatment, with the aim of reducing the dose delivered to the parotid glands and improving the dose coverage of complex target volumes located close to critical structures. The potential benefits of IMRT in terms of salivary function preservation and better local control have contributed to the rapid diffusion of this new technology. However, it should not be overlooked that IMRT is a novel treatment technique and that its clinical application represents a paradigm shift in the practice of radiation oncology. The purpose of this article is to review the clinical experience with IMRT for head and neck cancer treatment and to discuss some important issues related to its implementation.     

Patterns of failure and toxicity after intensity-modulated radiotherapy for head and neck cancer

PURPOSE: To determine the outcome of patients treated with intensity-modulated radiotherapy (IMRT) for head and neck cancer. METHODS AND MATERIALS: We reviewed the charts of 100 consecutive patients treated with IMRT for squamous cell carcinoma of the oropharynx (64%), nasopharynx (16%), hypopharynx (14%), and larynx (6%). Most patients were treated with a concomitant boost schedule to 72 Gy. Of the 100 patients, 54 (54%) received adjuvant chemotherapy, mostly concurrent cisplatin. The dosimetry plans for patients with either locoregional failure or Grade 4-5 complications were reviewed and fused over the computed tomography images corresponding with the location of the event. Marginal failures were defined as those that occurred at a region of high-dose falloff, where conventional fields would have provided better coverage. RESULTS: The median follow-up of living patients was 3.1 years (range, 1-5.2 years). The 3-year rate of local control, locoregional control, freedom from relapse, cause-specific survival, and overall survival for all patients was 89%, 87%, 72%, 78%, and 71%, respectively. The 3-year rate of freedom from relapse, cause-specific survival, and overall survival for the 64 oropharynx patients was 86%, 92%, and 84%, respectively. Of the 10 local failures, 2 occurred at the margin of the high-dose planning target volume. Both regional failures occurred within the planning target volume. No locoregional failures occurred outside the planning target volume. Of the 100 patients, 8 and 5 had Grade 4 and 5 complications from treatment, respectively. All patients with Grade 5 complications had received adjuvant chemotherapy. No attempt was made to discriminate between the complications from IMRT and other aspects of the patients' treatment. CONCLUSION: Intensity-modulated radiotherapy did not compromise the outcome compared with what we have achieved with conventional techniques. The 2 cases of recurrence in the high-dose gradient region highlight the potential hazard of approaches that involve highly conformal dose distributions.     

Positron emission tomography-guided, focal-dose escalation using intensity-modulated radiotherapy for head and neck cancer

PURPOSE: To assess the feasibility of intensity-modulated radiotherapy (IMRT) using positron emission tomography (PET)-guided dose escalation, and to determine the maximum tolerated dose in head and neck cancer. METHODS AND MATERIALS: A Phase I clinical trial was designed to escalate the dose limited to the [(18)-F]fluoro-2-deoxy-D-glucose positron emission tomography ((18)F-FDG-PET)-delineated subvolume within the gross tumor volume. Positron emission tomography scanning was performed in the treatment position. Intensity-modulated radiotherapy with an upfront simultaneously integrated boost was employed. Two dose levels were planned: 25 Gy (level I) and 30 Gy (level II), delivered in 10 fractions. Standard IMRT was applied for the remaining 22 fractions of 2.16 Gy. RESULTS: Between 2003 and 2005, 41 patients were enrolled, with 23 at dose level I, and 18 at dose level II; 39 patients completed the planned therapy. The median follow-up for surviving patients was 14 months. Two cases of dose-limiting toxicity occurred at dose level I (Grade 4 dermitis and Grade 4 dysphagia). One treatment-related death at dose level II halted the study. Complete response was observed in 18 of 21 (86%) and 13 of 16 (81%) evaluated patients at dose levels I and II (p < 0.7), respectively, with actuarial 1-year local control at 85% and 87% (p = n.s.), and 1-year overall survival at 82% and 54% (p = 0.06), at dose levels I and II, respectively. In 4 of 9 patients, the site of relapse was in the boosted (18)F-FDG-PET-delineated region. CONCLUSIONS: For head and neck cancer, PET-guided dose escalation appears to be well-tolerated. The maximum tolerated dose was not reached at the investigated dose levels.     

Optimized radiotherapy for head and neck cancer.

Optimization of radiation therapy for head and neck tumors requires the combination of several facets of radiation biology and physics. The aim is to achieve optimum tumor control while reducing normal tissue damage. Techniques have been developed to determine tumor radiosensitivity and growth characteristics. Their use as predictive assays of treatment response is gaining importance. As the range of therapeutic options (particularly altered fractionation regimens) increases, it is hoped that the ability to individually tailor patients' treatment will result in improved rates of tumor control and an improved therapeutic ratio. Optimization of treatment delivery based on three-dimensional treatment planning offers the opportunity for dose escalation studies and limitation of normal tissue morbidity. The combination of chemotherapy and radiotherapy continues to be investigated, although major advances using this strategy are unlikely.     

A comparison of forward and inverse treatment planning for intensity-modulated radiotherapy of head and neck cancer.

BACKGROUND AND PURPOSE: To compare intensity-modulated treatment plans of patients with head and neck cancer generated by forward and inverse planning. MATERIALS AND METHODS: Ten intensity-modulated treatment plans, planned and treated with a step&shoot technique using a forward planning approach, were retrospectively re-planned with an inverse planning algorithm. For this purpose, two strategies were applied. First, inverse planning was performed with the same beam directions as forward planning. In addition, nine equidistant, coplanar incidences were used. The main objective of the optimisation process was the sparing of the parotid glands beside an adequate treatment of the planning target volume (PTV). Inverse planning was performed both with pencil beam and Monte Carlo dose computation to investigate the influence of dose computation on the result of the optimisation. RESULTS: In most cases, both inverse planning strategies managed to improve the treatment plans distinctly due to a better target coverage, a better sparing of the parotid glands or both. A reduction of the mean dose by 3-11Gy for at least one of the parotid glands could be achieved for most of the patients. For three patients, inverse planning allowed to spare a parotid gland that had to be sacrificed by forward planning. Inverse planning increased the number of segments compared to forward planning by a factor of about 3; from 9-15 to 27-46. No significant differences for PTV and parotid glands between both inverse planning approaches were found. Also, the use of Monte Carlo instead of pencil beam dose computation did not influence the results significantly. CONCLUSION: The results demonstrate the potential of inverse planning to improve intensity-modulated treatment plans for head and neck cases compared to forward planning while retaining clinical utility in terms of treatment time and quality assurance.     

晚期肺癌非共面和共面IMRT剂量学比较研究

目的 比较研究晚期肺癌非共面IMRT计划剂量学分布特点,并观察计划执行安全性。方法 对14例晚期肺癌患者优化设计共面和非共面5、7个野IMRT计划,对比共面、非共面各组内及组间计划优化结果。观察4例患者非共面7个野计划的执行过程。结果 随射野数目增加共面及非共面靶区CI均改善(P值均为0.000),非共面野靶区D_mean、D_max、V_95%、HI亦有改善(P=0.001、0.001、0.009、0.000);共面野全肺、患、健肺V₅增加(P=0.000、0.002、0.000)及全肺D_mean增加(P=0.000),相反非共面野全肺、健肺V₅降低(P=0.001、0.005)。组间非共面7个野较共面5个野计划靶区各指标均改善(P值均为0.000);各肺V₂₀均降低(P值均为0.000)且全肺D_mean、V₃₀及健肺V₅降低(P=0.000、0.001、0.000),脊髓D_max亦有减少(P=0.033);但患肺V₅及心脏D_mean增加(P=0.000、0.003)。较共面7个野计划患肺V₅及心脏D_mean亦增加(P=0.000、0.048),但全肺及健肺V₅均降低(所有P=0.000)。4例患者均顺利完成非共面IMRT,全程未发生碰撞风险。结论 非共面7个野IMRT计划改善了靶区剂量分布,降低肺V₂₀、D_mean也控制了低剂量肺体积增加趋势且临床实施安全有效,值得推荐。     

Quality assurance program for intensity-modulated radiotherapy (IMRT) treatments of head and neck carcinomas]

A new technique such as intensity-modulated radiotherapy needs a quality assurance program. A French cooperative group joined to define a common program for the use of this technique in the case of head and neck carcinomas. Specific controls are necessary and even mandatory, for example: leaves position, speed of the leaves and the linearity of the dose with the monitor unit number. Measurements in homogeneous phantoms will validate calculated treatment plans. Absolute and relative measurements need ionisation chambers and films. Measurements for each beam, gantry at 0 degrees, are basic measurements. If those are impossible due to the treatment planning software, they can be performed with the treatment angles, films of course positioned perpendicularly to the beam axis. A consensus must be established between members to reduce the frequency and the number of measurements. Nevertheless, it currently seems mandatory to maintain measurements for each beam. Moreover, incidents that happen during this kind of treatment have to be recorded and new verifications will have to be realised then. This program is a unique possibility to match the application of a new technique whatever the type of equipment.     

18FDG] PET-CT-based intensity-modulated radiotherapy treatment planning of head and neck cancer

PURPOSE: To define the best threshold for tumor volume delineation of the (18) fluoro-2-deoxy-glucose positron emission tomography ((18)FDG-PET) signal for radiotherapy treatment planning of intensity-modulated radiotherapy (IMRT) in head and neck cancer. METHODS AND MATERIALS: In 25 patients with head-and-neck cancer, CT-based gross tumor volume (GTV(CT)) was delineated. After PET-CT image fusion, window level (L) was adapted to best fit the GTV(CT), and GTV(PET) was delineated. Tumor maximum (S) and background uptake (B) were measured, and the threshold of the background-subtracted tumor maximum uptake (THR) was used for PET signal segmentation. Gross tumor volumes were expanded to planning target volumes (PTVs) and analyzed. RESULTS: The mean value of S was 40 kBq/mL, S/B ratio was 16, and THR was 26%. The THR correlated with S (r = -0.752), but no correlation between THR and the S/B ratio was seen (r = -0.382). In 77% of cases, S was >30 kBq/mL, and in 23% it was 30% +/- 1.6% kBq/mL and 40% in tumors with S 相似文献   

Intraoperative radiotherapy for pre-irradiated head and neck cancer.

BACKGROUND AND PURPOSE: Radiotherapy of recurrent head and neck tumours is limited in dose due to pre-treatment up to normal tissue tolerance doses. Surgery alone is limited by the problems related to pre-surgery, post-radiation fibrosis, and infiltration of tumours into nerves and vessels too closely to be completely removed. Our aim was to evaluate the possible role of intraoperative radiotherapy (IORT) in such tumours treated with palliative intent. METHODS: In the last 10 years, we performed 113 intraoperative irradiations in a total of 84 pre-irradiated patients with head and neck cancer. The patient data were evaluated with regard to palliative effect, complications of treatment, recurrence and survival after IORT. RESULTS: Palliation of symptoms, as assessed by clinical evaluation, was achieved in 88% of symptomatic patients, often just by removal of large exophytic or exulcerating tumours, with IORT preventing their immediate recurrence after surgery. The complication rate did not exceed that expected after surgery alone. The median survival after IORT was 6.8 months, with a median time to local tumour recurrence or progression of 3.7 months. CONCLUSION: Intraoperative irradiation can be used as a palliative treatment option in pre-treated head and neck tumours with satisfactory results. With large and infiltrating tumours, however, recurrences or tumour progression occur close to the IORT portals, thus rendering this method unsuitable for achieving long-term control in such extended tumours.     

Patterns of local-regional recurrence following parotid-sparing conformal and segmental intensity-modulated radiotherapy for head and neck cancer

Purpose: To analyze the patterns of local-regional recurrence in patients with head and neck cancer treated with parotid-sparing conformal and segmental intensity-modulated radiotherapy (IMRT).

Methods and Materials: Fifty-eight patients with head and neck cancer were treated with bilateral neck radiation (RT) using conformal or segmental IMRT techniques, while sparing a substantial portion of one parotid gland. The targets for CT-based RT planning included the gross tumor volume (GTV) (primary tumor and lymph node metastases) and the clinical target volume (CTV) (postoperative tumor bed, expansions of the GTVs and lymph node groups at risk of subclinical disease). Lymph node targets at risk of subclinical disease included the bilateral jugulodigastric and lower jugular lymph nodes, bilateral retropharyngeal lymph nodes at risk, and high jugular nodes at the base of skull in the side of the neck at highest risk (containing clinical neck metastases and/or ipsilateral to the primary tumor). The CTVs were expanded by 5 mm to yield planning target volumes (PTVs). Planning goals included coverage of all PTVs (with a minimum of 95% of the prescribed dose) and sparing of a substantial portion of the parotid gland in the side of the neck at less risk. The median RT doses to the gross tumor, the operative bed, and the subclinical disease PTVs were 70.4 Gy, 61.2 Gy, and 50.4 Gy respectively. All recurrences were defined on CT scans obtained at the time of recurrence, transferred to the pretreatment CT dataset used for RT planning, and analyzed using dose–volume histograms. The recurrences were classified as 1) “in-field,” in which 95% or more of the recurrence volume (V_recur) was within the 95% isodose; 2) “marginal,” in which 20% to 95% of V_recur was within the 95% isodose; or 3) “outside,” in which less than 20% of V_recur was within the 95% isodose.

Results: With a median follow-up of 27 months (range 6 to 60 months), 10 regional recurrences, 5 local recurrences (including one noninvasive recurrence) and 1 stomal recurrence were seen in 12 patients, for a 2-year actuarial local-regional control rate of 79% (95% confidence interval 68–90%). Ten patients (80%) relapsed in-field (in areas of previous gross tumor in nine patients), and two patients developed marginal recurrences in the side of the neck at highest risk (one in the high retropharyngeal nodes/base of skull and one in the submandibular nodes). Four regional recurrences extended superior to the jugulodigastric node, in the high jugular and retropharyngeal nodes near the base of skull of the side of the neck at highest risk. Three of these were in-field, in areas that had received the dose intended for subclinical disease. No recurrences were seen in the nodes superior to the jugulodigastric nodes in the side of the neck at less risk, where RT was partially spared.

Conclusions: The majority of local-regional recurrences after conformal and segmental IMRT were “in-field,” in areas judged to be at high risk at the time of RT planning, including the GTV, the operative bed, and the first echelon nodes. These findings motivate studies of dose escalation to the highest risk regions.     

Swallowing-sparing intensity-modulated radiotherapy for head and neck cancer patients: Treatment planning optimization and clinical introduction

Purpose

To report on the potential benefits of swallowing-sparing intensity-modulated radiation therapy (SW-IMRT) in the first 100 SW-IMRT treated patients, as well as on the factors that influence the potential benefit of SW-IMRT relative to standard parotid sparing (ST)-IMRT.

Material and methods

One hundred consecutive head and neck cancer patients, scheduled for primary radiotherapy, were included in this prospective cohort study. For each patient, ST-IMRT and SW-IMRT treatment plans were created. All patients were eventually treated with SW-IMRT. Objectives for SW-IMRT were identical to those with ST-IMRT, with additional objectives to spare the swallowing organs at risk (SWOARs). After 20 patients, interim results were evaluated by a multidisciplinary committee.

Results

The mean gain of SW-IMRT relative to ST-IMRT in the first 20 patients was less than expected based on our previous planning comparative study. A critical review of all plans revealed that the results with SW-IMRT could be improved by: (1) gaining experience and attempting to reduce SWOAR dose as much as possible; (2) accepting a moderate shift of dose to unspecified tissues; (3) maximizing SWOAR sparing while keeping PTV coverage exactly according to protocol. In the additional 80 patients, the mean dose to the various SWOARs was further reduced significantly compared to ST-IMRT. Dose reductions with SW-IMRT were largest for patients who received neck irradiation, had a tumour located in the larynx, oropharynx, nasopharynx or oral cavity, and had <75% overlap between SWOARs and PTVs. The mean absolute reduction in predicted physician-rated RTOG grade 2–4 swallowing dysfunction for patients numbered 21–100 was 6.1%, ranging from 0.0% to 17.2%.

Conclusions

The benefit of SW-IMRT depends significantly on neck radiotherapy, tumour site and the amount of overlap between SWOARs and PTVs. Optimal clinical introduction requires a detailed evaluation and comparison between the standard (ST-IMRT) and new technique (SW-IMRT) in order to fully exploit the potential benefits.     

Modern radiotherapy for head and neck cancer

Radiation therapy (RT) plays a key role in curative-intent treatments for head and neck cancers. Its use is indicated as a sole therapy in early stage tumors or in combination with surgery or concurrent chemotherapy in advanced stages. Recent technologic advances have resulted in both improved oncologic results and expansion of the indications for RT in clinical practice. Despite this, RT administered to the head and neck region is still burdened by a high rate of acute and late side effects. Moreover, about 50% of patients with high-risk disease experience loco-regional recurrence within 3 years of follow-up. Therefore, in recent decades, efforts have been dedicated to optimize the cost/benefit ratio of RT in this subset of patients. The aim of the present review was to highlight modern concepts of RT for head and neck cancers considering both the technological advances that have been achieved and recent knowledge that has informed the biological interaction between radiation and both tumor and healthy tissues.     

Implementation of intensity-modulated radiotherapy for head and neck cancers in routine practice

Purpose

To report on patterns of relapse following implementation of intensity-modulated radiotherapy and subsequent changes in practice in a tertiary care centre.

Recurrence in region of spared parotid gland after definitive intensity-modulated radiotherapy for head and neck cancer

PURPOSE: To discuss the implications of three examples of periparotid recurrence after definitive intensity-modulated radiotherapy (IMRT) for head and neck cancer (HNC). METHODS AND MATERIALS: We present 3 patients with HNC who underwent definitive IMRT with concurrent chemotherapy and later had treatment failure in or near a spared parotid gland. Two patients had bilateral multilevel nodal disease, and all had Level II nodal disease ipsilateral to the site of recurrence. The patients were treated using dose-painting IMRT with a dose of 70 Gy to the gross tumor volume and 59.4 Gy or 54 Gy to the high-risk or low-risk clinical tumor volume, respectively. The parotid glands were spared bilaterally. The patients had not undergone any surgical treatment for HNC before radiotherapy. RESULTS: All patients had treatment failure in the region of a spared parotid gland. Failure in the 2 patients with bilateral multilevel nodal involvement occurred in the periparotid lymph nodes. The third patient developed a dermal metastasis near the tail of a spared parotid gland. On pretreatment imaging, the 2 patients with nodal failure had small nonspecific periparotid nodules that showed no hypermetabolic activity on positron emission tomography. CONCLUSION: For HNC patients receiving definitive IMRT, nonspecific positron emission tomography-negative periparotid nodules on pretreatment imaging should raise the index of suspicion for subclinical disease in the presence of multilevel or Level II nodal metastases. Additional evaluation of such nodules might be indicated before sparing the ipsilateral parotid gland.     

宫颈癌术后盆腔容积调强弧形治疗与固定野调强放疗计划的剂量学研究

目的 研究宫颈癌术后患者应用固定野调强放疗(FF-IMRT)和容积调强弧形治疗(VIMAT)计划剂量学差异。方法 选择 13例宫颈癌术后调强放疗患者CT模拟定位并勾画靶区及危及器官,对同一CT图像设计FF-IMRT计划和VIMAT计划,评估计划靶体积(PTV)及危及器官的剂量学参数。两种计划参数比较用配对t检验。结果 与FF-IMRT计划相比,VIMAT计划PTV的95%覆盖度增加(t=9.84,P=0.000)、110%覆盖度降低(t=－3.72,P=0.003)、最大剂量(D_max)降低(t=－3.51,P=0.005)、适形指数变差(t=5.93,P=0.000),但PTV105%覆盖度、平均剂量(D_mean)、不均匀指数均相似(t=－0.02、－0.60、1.13,P=0.842、0.560、0.283);膀胱 V₃₀降低约10%(t=－4.99,P=0.000)、D_mean降低1.4 Gy (t=－3.65,P=0.004)、D_max降低1.5 Gy (t=－18.03,P=0.000),直肠 V₄₀降低约10%(t=－2.99,P=0.012),D_mean降低0.6 Gy (t=－2.98,P=0.013)、D_max降低0.8 Gy (t=－4.05,P=0.002),小肠 V₄₀降低最多(10%)(t=－4.74,P=0.001)、D_max降低0.8 Gy (t=－9.45,P=0.000),骨髓 V₅₀降低最多(16%)(t=－4.04,P=0.002)、D_mean降低1.9 Gy (t=－16.21,P=0.000),左、右股骨头 D₅和马尾神经 D_max分别降低1.6、2.7 Gy和1.5 Gy (t=－2.89、－6.22、－4.80,P=0.015、0.000、0.001);机器跳数减少57%(t=－40.54,P=0.000)。结论 宫颈癌患者采用VIMAT技术可获得等同于或优FF-IMRT计划的剂量分布,机器数量明显降低,但其疗效还需进一步临床评估。     

Comparison of intensity-modulated radiotherapy, adaptive radiotherapy, proton radiotherapy, and adaptive proton radiotherapy for treatment of locally advanced head and neck cancer

Background and purpose

Various radiotherapy planning methods for locally advanced squamous cell carcinoma of the head and neck (SCCHN) have been proposed to decrease normal tissue toxicity. We compare IMRT, adaptive IMRT, proton therapy (IMPT), and adaptive IMPT for SCCHN.

Materials and methods

Initial and re-simulation CT images from 10 consecutive patients with SCCHN were used to quantify dosimetric differences between photon and proton therapy. Contouring was performed on both CTs, and plans (n = 40 plans) and dose-volume histograms were generated.

Results

The mean GTV volume decreased 53.4% with re-simulation. All plans provided comparable PTV coverage. Compared with IMRT, adaptive IMRT significantly reduced the maximum dose to the mandible (p = 0.020) and mean doses to the contralateral parotid gland (p = 0.049) and larynx (p = 0.049). Compared with IMRT and adaptive IMRT, IMPT significantly lowered the maximum doses to the spinal cord (p < 0.002 for both) and brainstem (p < 0.002 for both) and mean doses to the larynx (p < 0.002 for both) and ipsilateral (p = 0.004 IMRT, p = 0.050 adaptive) and contralateral (p < 0.002 IMRT, p = 0.010 adaptive) parotid glands. Adaptive IMPT significantly reduced doses to all critical structures compared with IMRT and adaptive IMRT and several critical structures compared with non-adaptive IMPT.

Conclusions

Although adaptive IMRT reduced dose to several normal structures compared with standard IMRT, non-adaptive proton therapy had a more favorable dosimetric profile than IMRT or adaptive IMRT and may obviate the need for adaptive planning. Protons allowed significant sparing of the spinal cord, parotid glands, larynx, and brainstem and should be considered for SCCHN to decrease normal tissue toxicity while still providing optimal tumor coverage.     

Impact of intensity-modulated radiotherapy on health-related quality of life for head and neck cancer patients: matched-pair comparison with conventional radiotherapy

PURPOSE: To assess the benefit of intensity-modulated radiotherapy (IMRT) compared with conventional RT for the quality of life (QOL) of head and neck cancer survivors. METHODS AND MATERIALS: Cross-sectional QOL measures (European Organization for Research and Treatment of Cancer QOL questionnaire C30 and head and neck cancer module) were used with a French multicenter cohort of patients cured of head and neck cancer (follow-up > or = 1 year) who had received bilateral neck RT (> or = 45 Gy) as a part of their initial treatment. We compared the QOL mean scores regarding RT modality (conventional RT vs. IMRT). The patients of the two groups were matched (one to one) according to the delay between the end of RT and the timing of the QOL evaluation and the T stage. Each QOL item was divided into two relevant levels of severity: "not severe" (responses, "not at all" and "a little") vs. "severe" (responses "quite a bit" and "very much"). The association between the type of RT and the prevalence of severe symptoms was approximated, through multivariate analysis using the prevalence odds ratio. RESULTS: Two comparable groups (67 pairs) were available. Better scores were observed on the head and neck cancer module QOL questionnaire for the IMRT group, especially for dry mouth and sticky saliva (p < 0.0001). Severe symptoms were more frequent with conventional RT concerning saliva modifications and oral discomfort. The adjusted prevalence odds ratios were 3.17 (p = 0.04) for dry mouth, 3.16 (p = 0.02) for sticky saliva, 3.58 (p = 0.02) for pain in the mouth, 3.35 (p = 0.04) for pain in the jaw, 2.60 (p = 0.02) for difficulties opening the mouth, 2.76 (p = 0.02) for difficulties with swallowing, and 2.68 (p = 0.03) for trouble with eating. CONCLUSION: The QOL assessment of head and neck cancer survivors demonstrated the benefit of IMRT, particularly in the areas of salivary dysfunction and oral discomfort.     

Recurrences after conformal parotid-sparing radiotherapy for head and neck cancer.

BACKGROUND AND PURPOSE: Evaluation of loco-regional failure patterns and survival after parotid-sparing three-dimensional conformal and intensity modulated radiotherapy (IMRT) for head and neck cancer. PATIENTS AND METHODS: From June 1999 to July 2002, seventy-two patients with lateralised head and neck tumours, excluding nasopharyngeal tumours and patients with bilateral or contralateral neck disease, were irradiated with a parotid-sparing technique. Three-dimensional conformal planning was used in 68 patients, 4 patients were treated with dynamic IMRT. Bilateral neck node irradiation was performed in all patients, the junctional (or high level II) nodes, contralateral to the tumour, however, were excluded from the clinical target volume to spare the adjacent parotid from irradiation. In 20 patients with persistent or recurrent loco-regional disease, the localisation and volume of the treatment failure, as determined by computed tomography (CT), was copied on the pre-treatment CT-study used for treatment planning. Minimum, mean and maximum doses administered to the region of the failure were calculated and dose--volume histograms were computed of each failure. The failures were divided in three groups depending on the percentage of their volume receiving 95% of the prescribed dose. Recurrences were defined to be in-field (IF) if >95% of their volume received 95% of the prescribed dose and out-field (OF) if <20% of their volume received 95% of the prescribed dose. When 20-95% of the volume of the recurrence received 95% of the prescribed dose, this recurrence was defined as extending outside the field (EOF). RESULTS: With a median follow-up time of 19 months, the 2-year loco-regional control rate was 69% with primary radiotherapy and 63.5% with surgery followed by irradiation (P = 0.77). The 2-year overall survival rate for the entire patient population was 67.4%. At the time of analysis, 20 of the 72 patients had developed a loco-regional failure; 2 patients (2/20) presented with a loco-regional relapse combined with distant metastasis. Fifteen of the 20 loco-regional failures (15/20) occurred within the high dose region (IF). Five patients (5/20) developed a failure of which the bulky tumour mass was located within the high dose region but extending outside the treatment volume (EOF). No relapses were seen out-field (OF) and no patients relapsed in the spared junctional area contralateral to the tumour. CONCLUSIONS: The selection of patients treated with parotid-sparing radiotherapy, by omitting irradiation to the junctional nodes contralateral to the tumour, proved to be safe in our hands, since no recurrences developed in the spared area. As this parotid-sparing technique reduces significantly the dose to the contralateral parotid and is easy to perform, it should be considered for all selected patients.