Treatment Techniques and Site Considerations Regarding Dysphagia-Related Quality of Life in Cancer of the Oropharynx and Nasopharynx
Tequh IJROBP 2008;72:1119

Purpose

To assess the relationship for oropharyngeal (OP) cancer and nasopharyngeal (NP) cancer between the dose received by the swallowing structures and the dysphagia related quality of life (QoL).

Methods and Materials

Between 2000 and 2005, 85 OP and 47 NP cancer patients were treated by radiation therapy. After 46 Gy, OP cancer is boosted by intensity-modulated radiation therapy (IMRT), brachytherapy (BT), or frameless stereotactic radiation/cyberknife (CBK). After 46 Gy, the NP cancer was boosted with parallel-opposed fields or IMRT to a total dose of 70 Gy; subsequently, a second boost was given by either BT (11 Gy) or stereotactic radiation (SRT)/CBK (11.2 Gy). Sixty OP and 21 NP cancer patients responded to functional and QoL questionnaires (i.e., the Performance Status Scales, European Organization for Research and Treatment of Cancer H&N35, and M.D. Anderson Dysphagia Inventory). The swallowing muscles were delineated and the mean dose calculated using the original three-dimensional computed tomography–based treatment plans. Univariate analyses were performed using logistic regression analysis.

 

Schematic diagram of the delineated five muscular structures considered of paramount importance in swallowing.

  

Results

Most dysphagia problems were observed in the base of tongue tumors. For OP cancer, boosting with IMRT resulted in more dysphagia as opposed to BT or SRT/CBK. For NPC patients, in contrast to the first booster dose (46–70 Gy), no additional increase of dysphagia by the second boost was observed.

Conclusions

The lowest mean doses of radiation to the swallowing muscles were achieved when using BT as opposed to SRT/CBK or IMRT. For the 81 patients alive with no evidence of disease for at least 1 year, a dose–effect relationship was observed between the dose in the superior constrictor muscle and the “normalcy of diet” (Performance Status Scales) or “swallowing scale” (H&N35) scores (p < 0.01).

 

Definitions and delineations of the swallowing muscles of the swallowing apparatus on a sagital computed tomography slice.

  

Discussion 

With regard to the swallowing mechanism, the following anatomic structures were identified: the superior constrictor muscle (scm), the middle constrictor muscle (mcm), the inferior constrictor muscle (icm), the cricopharyngeal muscle (cphm), and the first centimeter of the muscular compartment of the esophagus inlet.  From the current literature, we know that the intensification of therapy for head-and-neck cancer in general results in improved locoregional tumor control. However, late sequelae also increase, including swallowing disorder. Limited data on swallowing problems are reported before 2005. Recently, increased attention is given to the swallowing problem because of the ongoing randomized clinical trials in dysphagia. The prevalence of dysphagia in organ preservation therapy is reported to be as high as 50%. A study by Eisbruch  showed that elevation of the larynx and pharynx during swallowing is essential for protection of the airway and propulsion of the bolus. After chemoradiation, there is decreased base of tongue or posterior pharyngeal contraction and reduced pharyngeal contraction, resulting in impaired bolus transport through the pharynx. Logemann et al. concludes that there is little if any difference in frequency of swallowing problems across different disease sites after treatment and according to the same authors that the effects of the different chemotherapy agents were seemingly small. Pretreatment swallowing therapy may improve dysphagia and reduce the need for tube feedings. Feng et al. demonstrated significant relationships between dose–volume parameters of structures and objective and subjective measurements of swallowing dysfunction. Other groups also showed significant correlations of various dysphagia endpoints with dose: the supraglottic lesions and glottic cancers.

This article analyzes the dose–volume relationships for dysphagia (and xerostomia). It particularly relates the side effects (QoL) to different treatment techniques and to widely separated anatomic locations; that is the BOT, the tonsillar fossa or soft palate, and the nasopharynx. From our series of 132 patients, chart review showed that 24 (18%) patients experienced moderate to severe dysphagia (Radiation Therapy Oncology Group Grade 3 and 4) with more problems in patients with BOT (32%) cancer as opposed to patients with cancer of the TF/SP (22%) and NP (6%). Although correlations between the questionnaires were poor, almost one third of the patients' complain of swallowing disorders. Moreover, patients seem to experience more complaints of dysphagia with longer follow-up (this finding is part of a separate article in preparation). If grouped by treatment technique, most severe dysphagia was found in IMRT/3D-CRT compared with BT group and SRT/CBK group. One explanation could be the cumulative dose in the swallowing structures. For example, if treated by EBRT techniques, the mean dose in the scm was 70 Gy in case of BOT tumors, 64 Gy in TF/SP, and 67 Gy in NPC. If the booster is given by BT, the highest mean dose in scm is 52 Gy for BOT and 42 Gy for TF/SP. However, comparing dose distributions in TF/SP, BOT, and NP, it can be seen that in the scm and mcm the highest dose was found in patients with NPC. The NPC patient category is always treated (per protocol) by a large volume boost dose (so called first boost) of 24 Gy by EBRT techniques to a cumulative dose of 70 Gy to the primary tumor and positive neck nodes. It is unclear to us why the patients with NPC treated by a high dose to the upper swallowing muscles do not complain of dysphagia to the same extent compared with, for example, BOT cancer patients. One possible explanation could be the infiltrating nature of the disease itself in the case of BOT cancers. The BT or SRT/CBK booster dose in NPC is, however, of no relevance to the scm and other muscles given the very small volume and rapid dose falloff.

Several dose–effect relationships between dysphagia problems and the dose received by the swallowing muscles were found to be significant. Most significant were the relationships between EORTC H&N35 and the dose in the scm/mcm and the association of the PSS (normalcy of diet) and the dose in the scm (p values < 0.01). The higher the dose, the more chance of complaints of dysphagia. Xerostomia and dysphagia are strongly associated. Particularly highly correlated were the questions of the EORTC H&N35 questionnaire regarding swallowing, dry mouth, and sticky saliva.

 

Conclusions 

Patients treated with a variety of disease sites (TF/BOT/NPC) and treated by various RT techniques (IMRT/3D-CRT/BT/SRT/CBK) vary in their prevalence of severe dysphagia. Responses to QoL questionnaires in relation to the dose received by scm and mcm demonstrated a dose–effect relationship. Dysphagia is also site (geographic position)-dependent; most dysphagia problems are seen in BOT cancer patients. Although NPC patients receive the highest dose because of the treatment techniques used, dysphagia is still less as opposed to patients with cancer of the BOT. The explanation of this phenomenon remains somewhat unclear; it is speculated that this might have to do with the infiltrative (muscles) nature of the BOT cancers. Dysphagia is obviously multifactorial. In particular, dysphagia is strongly correlated with xerostomia. From the findings of the present research, we would like to emphasize for the future to focus more on treatment planning research (constraints), especially for issues like this frequently underreported dysphagia problem.