The purpose of this review was to find out what impact the tumour and chemoradiation has on voice and/or speech in patients with advanced head and neck cancer.
The literature search that was carried out for this review revealed only few studies that measured voice and/or speech. Of these, a total of 20 studies met the inclusion criteria. Although publications from 1990 till November 2009 were included, thus covering a period of almost 20 years, the studies that met the criteria were almost all published within the last 10 years. This indicates that voice and speech outcomes were of rather secondary interest in earlier organ preservation protocols suggesting that after organ preservation intact function preservation was taken for granted. It seems that only in the last decade clinicians have come to realise that organ and function preservation are not necessarily synonymous.
Of the retrieved hits, most studies focused on the overall survival or toxic effects, usually comparing organ preservation with surgical treatment. There were hardly studies that focused on findings or variations within a homogeneous CRT group of patients, and often, the patient groups included patients that also underwent surgery.
Of the 20 included studies, 14 reported on voice and 10 on speech, an important distinction that too seldom is made. CRT patients scored worse on the voice and speech scores as compared to normal laryngeal speakers, but better as compared to patients who received surgical treatment. In general, the preference of CRT over surgery combined with radiotherapy thus seems to be justified, although there were still severe negative effects. Overall, the studies indicated that voice and speech degenerated during CRT treatment, and improved again 1–2 months after treatment, exceeding pre-treatment levels after 1 year or longer. However, voice and speech measures did not show normal values, neither before, nor after treatment.
More data and studies that are more precise and that include pretreatment measurements are needed to evaluate posttreatment voice and speech quality in the long run. Given unexplained dropouts, unclear follow ups, missing reliability and validity of the tools, no intra- and interrater checks, missing baseline measures, various and small number of patients, unknown accrual times, and the lack of uniformity between the studies, the findings were not very reliable. Next to this, the replication potential was small.
Only one of the studies discussed in this review made explicitly a difference between tumours originating from the oral cavity and pharyngeal area and tumours originating from the larynx [29
]. The merged results of laryngeal and non-laryngeal cancer patients (and lacking information on radiation to the lymph nodes) make any interpretation of alternations of voice and speech due to cancer and the treatment by various CRT difficult. Only two studies made a distinction between the effects of tumour and treatment [20
In laryngeal cancers, one would expect the tumour to impede vocal fold movement, resulting in deteriorated voice quality. In non-laryngeal cancers, one would expect the tumour to have a negative effect on articulation, and therewith speech. With the treatment-induced shrinkage of the tumour, voice and speech, respectively, should improve, and lasting negative effects would be attributed to inherent anatomical changes (e.g. scars), radiation oedema and/or fibrosis. One goal of this review was to systematically assess and disentangle these effects of the tumour and its treatment by CCRT on voice and speech. However, due to the inconsistent information in the studies on e.g. tumour location, this aim could not be met.
Several factors were left unmentioned, such as the effects of speech-, voice- or swallowing therapy, tracheotomy, gastrostomy or radiotherapy to the salivary glands or lymph nodes. Furthermore, not only there was a large range in follow-up periods, also, in several studies, the follow-up time metering started with the initiation of treatment, whereas in other studies, metering started with the end of treatment, making a comparison more cumbersome.
There were 18 different measurement instruments and most of these tools are quality of life measures, assessing voice and speech outcomes rather superficially. Especially the standardised, validated questionnaires are ‘poorly equipped’ with voice and speech items, underlining the importance of (also) using study/topic specific questionnaires [33
]. In addition, in general, terminology and assessment of voice and speech problems are often incompletely separated. This review underlines that the 18 tools used not only showed a wide variation (acoustic/EGG measurements, and patient-based, and/or clinician-based questionnaires), but also that several of these tools were not standardised, and often, interrater reliability and/or validity were not reported.
Almost all studies based their outcome on one-dimensionally assessed data; the most favored method of assessment was the patient questionnaire. Given the often limited number of patients, this is probably the ‘easiest’ method of voice and speech quality assessment, as no clinician or equipment needs to be involved. Although these questionnaires provide a relevant view on the patient’s perceived quality of life, they do not necessarily reflect the patient’s actual physical status, and organ functioning, or the clinician’s perception. There is a lack of studies that compare the outcome of voice- and in particular speech in different assessment dimensions to verify the extent or feasibility for each subjective or objective dimension of measurement, and its clinical indication.
This systematic review showed that the need for more dimensional assessment of organ functioning was hardly ever mentioned, although it is obvious that multi-dimensional assessment is mandatory [23
Proposed protocols are available for the analysis of voice, e.g. by Verdonck-de Leeuw et al. [35
], Meleca et al. [23
], or Dejonckere et al. [10
]. All agree in suggesting a multi-dimensional subjective and objective analysis. Suggestions for speech assessment protocols for cancer patients are not yet available, but certainly needed, because it is obvious that tumour- or treatment-related articulatory disorders strongly affect the intelligibility of speech. Usually, clinician- and/or patient-based tools are used to assess intelligibility and articulatory abilities of the patient. However, human perception always carries a subjective imprint, and a clinician-based analysis with various listeners is rather time expensive and impractical in a clinical setting. Therefore, comparable to the proposed multi-dimensional protocols for voice analysis, a similar tool for the analysis of speech should include at least a patient questionnaire on speech and intelligibility, together with acoustic analyses and e.g. the F-LTOAC. In future, if they succeed in copying the behaviour of either a normal representative listener or that of an experienced clinician, automatic speech intelligibility analyses, which are less costly in time, might help in this respect [36
The studies mentioned in this systematic review provide only a superficial picture of the effects of cancer and CRT on voice and speech in patients with advanced head and neck cancer. Considering the changes of voice and speech quality posttreatment, more and more precise, preferably prospective studies are needed, including both baseline measurements and a standardised assessment protocol that covers all relevant functional aspects of voice and speech.