Articulatory-kinematic changes in speech following surgical treatment for oral or oropharyngeal cancer: A systematic review.

Most studies were very small: the median number of people treated for oral or oropharyngeal cancer was five per study, and only six studies had more than 10, so no individual finding rests on many patients. Patient groups within and across studies were mixed in tumour stage, site, reconstruction and radiation, and the authors say this made a pooled analysis impossible; the conclusions rest on combining studies that measured different things in different ways. Risk of bias was moderate or high in 25 of the 29 studies (86.2%), largely from incomplete descriptions of patients, unclear inclusion and exclusion criteria, and control groups that were not matched for age. Controls were on average 16.6 years younger than the treated group (35 versus 53 years), and speech motor control changes with age. Nothing here applies to people treated without surgery: every included study treated participants surgically, and no study examined radiation or chemoradiation as the primary treatment. Only four studies included people who had received speech therapy and 16 did not say either way, so the review cannot tell you how therapy interacts with these movement changes, or whether the patterns described are what you would see in patients who have had treatment. Prospective studies followed people for at most 12 months, so there is no evidence about long-term change; the time-course results were contradictory and came from groups of one to five people. The authors rate the overall quality of the evidence as low or very low for all included studies, and the review notes that many studies gave qualitative rather than numerical descriptions of movement.

The authors report no conflict of interest. The named funder is Rijksuniversiteit Groningen (University of Groningen). The paper gives no further statement about the funder's role in the review.

Do not read this as a prediction for any individual patient. Most of the included studies had five or fewer people treated for cancer, more than half were retrospective, and the authors themselves rate the body of evidence low or very low, so what is described here is a map of what has been observed across very small surgical groups, not a forecast of how a particular patient's speech will change. Do not apply it to patients treated with radiation or chemoradiation alone, because no included study looked at them.