Cognitive social capital linked to saliva-related quality of life in cancer survivors

In a cross-sectional study of 105 adults treated for head and neck cancer, survivors with lower scores on a three-item cognitive social capital proxy index had poorer patient-reported saliva-related quality of life. After adjustment for education, tumour location, radiotherapy and time since treatment completion, a score below three was associated with an average 18.53-point lower University of Washington Quality of Life questionnaire saliva-domain score than the maximum score of three. The estimate was precise enough to exclude no difference at the conventional 5% level, with a 95% confidence interval of −33.85 to −3.21 and p=0.018, but its width means that the size of the association remains uncertain.

The researchers described the findings as preliminary and called for confirmation in larger longitudinal studies. The saliva-domain score measures perceived dry-mouth problems rather than objective salivary-gland function or hyposalivation. Across the study population, the mean score was 61.85 out of 100, with a standard deviation of 33.90 and a median of 67.00; the interquartile range was 33.00 to 100.00.

Saliva and taste had the lowest mean scores among the questionnaire’s 12 domains, followed by chewing. The use of this disease-specific outcome means that the analysis focused on a particular reported problem after head and neck cancer treatment rather than on overall quality of life or measured saliva production. Cognitive social capital was assessed through three proxy indicators selected for perceived support during adverse situations, trust in friends and neighbours, and perceived good relationships in the neighbourhood.

Affirmative responses—“Yes” or “Sometimes”—each received one point, while “No” received zero, yielding a possible index score from zero to three. This three-item index was not a shortened form of an existing instrument and had not been formally validated in head and neck cancer survivors. Its distribution had a pronounced ceiling effect: 87 of 105 participants, or 82.9%, scored the maximum of three, while 18, or 17.1%, scored below three.

That distribution determined how the primary analysis grouped participants. The reference group consisted of the 87 survivors who answered “Yes” or “Sometimes” to all three items, whereas the 18 participants who answered “No” to at least one item formed the lower-score group. The researchers also tested the index as a continuous zero-to-three variable and used an alternative coding in which only “Yes” responses earned a point.

The primary comparison therefore captured a sharp contrast between the maximum score and all lower scores, rather than estimating a smooth relationship across the full range of the index. Adults were recruited consecutively from the Head and Neck Surgery outpatient clinic of the Hospital Universitário de Santa Maria, a public teaching hospital in Rio Grande do Sul, southern Brazil. Eligibility required that participants had completed curative-intent treatment for squamous cell carcinoma of the lip, oral cavity, oropharynx, hypopharynx or larynx at least three months before data collection.

Data were collected from January 2023 to July 2025. Of 124 eligible people invited, 105 agreed to participate, producing a response rate of 84.7%. The mean age was 63.95 years, 85.7% of participants were male, 69.5% had fewer than eight years of formal education, and 81.9% received radiotherapy.

Clinical patterns in the sample were consistent with the importance of tumour location, radiation exposure and survivorship time to saliva-related outcomes. In the fully adjusted model, radiotherapy was associated with a 25.34-point lower saliva-domain score than no radiotherapy, with a 95% confidence interval of −40.91 to −9.77. Tumours in the hypopharynx or larynx were associated with an 18.07-point higher score than tumours in the lip, oral cavity or oropharynx, with a 95% confidence interval of 5.83 to 30.31.

A time since treatment of 26.2 months or less, the sample median, was associated with a 17.97-point lower score than a longer interval, with a 95% confidence interval of −29.84 to −6.09. The median treatment interval was 26.2 months, and individual times ranged from 3 to 192 months. Before adjustment, a cognitive social capital score below three was associated with an 18.86-point lower mean saliva-domain score, with a 95% confidence interval of −35.96 to −1.76 and p=0.031.

The cognitive social capital variable alone accounted for 4.4% of the variance in saliva-domain scores. Adding education increased the model’s explained variance to 9.3%, while the fully adjusted model—including cognitive social capital, education, tumour location, radiotherapy and time since treatment completion—explained 28.1% of the variance, with an adjusted R-squared of 0.245. The fully adjusted social-capital estimate remained similar to the unadjusted result, and education was no longer associated with the outcome after the clinical variables were included.

Sensitivity analyses produced estimates in the same direction. When the original index was entered as a continuous zero-to-three variable, each additional point was associated with a 12.36-point higher adjusted saliva-domain score, with a 95% confidence interval of 0.95 to 23.77 and p=0.034. Under the alternative coding, each point was associated with a 7.70-point higher score, with a 95% confidence interval of 0.99 to 14.41 and p=0.025.

Additional adjustment for tumour stage, treatment of time since completion as a continuous variable, and bias-corrected and accelerated bootstrap confidence intervals based on 1,000 resamples all yielded similar findings. The primary estimate after stage adjustment was −18.66 points, while the continuous-time estimate was −17.93 points. The results do not show that cognitive social capital prevents or reverses radiation-induced damage to salivary glands, and they do not establish that social relationships improve objective salivary flow.

The authors proposed several possible, but untested, routes through which perceived trust, reciprocity and support might relate to the subjective burden of dry mouth. These included access to information and professional care, help with transport, appointments and daily activities, adoption of symptom-management strategies, and emotional support. The same reasoning leaves open the reverse pathway: persistent oral dryness and associated difficulties might reduce social participation and alter how survivors perceive their relationships.

Negative affectivity could also influence both symptom reporting and perceptions of social resources. Because the study was cross-sectional, it could not determine the temporal sequence of these relationships. Several limitations restrict the conclusions and their generalisability.

Only 18 participants scored below three on the cognitive social capital proxy, limiting statistical precision and the ability to detect smaller associations. The proxy captured selected features of trust, support and neighbourhood relationships but was not a validated multidimensional measure and may overlap with perceived social support. Both the social-capital index and saliva-domain outcome were self-reported, creating the possibility of reporting bias.

The model also left most variation unexplained, and unmeasured factors could include radiation dose to major salivary glands, radiotherapy technique, concurrent chemotherapy, HPV status, xerogenic medications, comorbidities, tobacco and alcohol use, dental status, use of saliva substitutes or sialogogues, and objective salivary flow. Recruitment at a single public healthcare service may further restrict applicability to other healthcare systems and socioeconomic settings. The authors identified multicentre longitudinal research with repeated social-capital and saliva-related measurements, fuller social-capital instruments and objective salivary assessment as necessary next steps.

Subject of Research: Association of a three-item cognitive social capital proxy with patient-reported saliva-related quality of life in head and neck cancer survivors

Article Title: Association between cognitive social capital and saliva-related quality of life among head and neck cancer survivors: a cross-sectional study

Article References: Darós, A. C., Knorst, J. K., Emmanuelli, B., de Almeida Gonçalves, J. A., Antoniazzi, R. P., & Ferrazzo, K. L. (2026). Association between cognitive social capital and saliva-related quality of life among head and neck cancer survivors: a cross-sectional study. Supportive Care in Cancer, 34(11), Article 1141. https://doi.org/10.1007/s00520-026-11361-y

Image Credits: AI Generated

DOI: 10.1007/s00520-026-11361-y

Keywords: head and neck cancer, survivors, cognitive social capital, saliva-related quality of life, dry mouth, radiotherapy, patient-reported outcomes, cross-sectional study, oral health, psychosocial factors, Association, between