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Females Have Lower Salivary Flow Than Males 

The latest publication from the OraRad study team demonstrates that female patients have significantly lower salivary flow than males, before and after radiation therapy for head and neck cancer. The finding of lower salivary flow in females even before the start of radiation therapy, combined with prior literature in other populations and age groups, indicates that in general, females have lower salivary flow than males.

Reduced salivary flow (hyposalivation) is associated with increased risk for dental caries and some other oral conditions. The objective measurement of salivary flow is therefore important for risk assessment and to guide management strategies. This is usually done by measuring stimulated and/or unstimulated whole salivary flow over a defined period of time. Typically, the same standard normal values are used for both males and females in interpreting results of salivary flow testing. However, new findings from the OraRad study team demonstrate that females have significantly lower stimulated salivary flow than males, before and after radiation therapy for head and neck cancer.

Before the start of radiation therapy, the mean stimulated whole salivary flow rate was 0.81 g/min in females (n=107) as compared to 1.20 g/min in males (n=391) (p<0.001). At 18 months after radiation therapy, the mean stimulated whole salivary flow rate was 0.49 g/min in females and 0.70 g/min in males (p<0.001). The median nadir salivary flow after radiation therapy was 0.22 g/min in females and 0.35 g/min in males (p<0.001).

Furthermore, the authors cite several previous studies that demonstrate that this variation in salivary flow between sexes is not restricted to the head and neck cancer population. Lower stimulated and unstimulated salivary flow rates in females have been demonstrated in various populations of different age groups. Therefore, this difference in salivary flow between sexes appears to be a general finding. Since females as a group have lower normal salivary flow than males, they may be at higher risk for oral disease in situations where salivary flow is pathologically reduced. Thus, these findings have important implications for clinical practice and research.

The citation for the article is:

Lalla RV, Helgeson ES, Virk K, Lu H, Treister NS, Sollecito TP, Schmidt BL, Patton LL, Lin A, Brennan MT. Females have lower salivary flow than males, before and after radiation therapy for head/neck cancer. Oral Diseases. Published online 15 July 2024.

https://pubmed.ncbi.nlm.nih.gov/39005202/

The OraRad study is funded by the National Institute for Dental and Craniofacial Research (NIDCR) through grant U01DE022939, awarded to the study principal investigators Drs. Michael Brennan and Rajesh Lalla. The Program Officer is Dr. Dena Fischer.

Rajesh V. Lalla, D.D.S., Ph.D.        

Michael T. Brennan, DDS, MHS