Cancer treatment should start from the moment the patient receives a confirmed diagnosis and it involves a series of multi-professional interventions including surgery, radiotherapy, chemotherapy, hormone therapy, and target therapy. For cases treated with hormone therapy, the main drugs used to treat breast cancer are tamoxifen (TMXO), when there are estrogen receptors in the tumor mass that inhibit its production; and anastrozole, an aromatase inhibitor (AI) that also works on estrogen in postmenopausal women. For the condition of prostate cancer, the hormone therapy drug bicalutamide works by inhibiting androgenic hormones [1, 2, 3]. Choosing one medication over another is determined, among other factors, by the type and stage of the tumor. While using tamoxifen is recommended to premenopausal women, postmenopausal women may use both tamoxifen and anastrozole [2]. Bicalutamide has been indicated by the FDA for the metastatic treatment of prostate cancer [3]. When administered orally, its action may be affected by the concomitant use of other drugs and cause adverse effects in the oral cavity.
Studies have shown that estrogen is important for the maintenance of bone and soft tissues in the oral cavity. Thus, drugs that affect the production and prevent or complicate the connection of estrogen to its receptors, such as anastrozole, may affect bone and soft tissues in the oral cavity, increase the risk of periodontal disease, change the taste, decrease salivary flow, and cause xerostomia [2,4].
Xerostomia is characterized by the sensation of dry mouth and it may be primary or secondary. Primary xerostomia is characterized by the decrease in resting or stimulated saliva production, and secondary xerostomia is characterized by the dryness of the mouth with the absence of changes in salivary flow. Xerostomia and changed salivary flow may occur from changes in saliva composition, radiation in the head and neck region, smoking habit, alcoholism, and excess coffee intake, which are among the local factors that may lead to xerostomia [5,6,7,8,9].
Patients with xerostomia may find it difficult to eat and/or speak and present a burning sensation, halitosis, and change in taste. Lip dryness, oral candidosis, and dental caries may also be present even if the patient has good oral hygiene. Identifying the etiological factor early and consequently determining the diagnosis, either primary or secondary, will allow introducing a better and more effective treatment plan aiming at control and comfort, especially to women older than 60 years [5,7,8].
The literature is scarce on the relationship between xerostomia and/or hyposalivation and the use of hormone therapy drugs. As for the use of bicalutamide for patients with prostate cancer, there are no studies available. The studies related to the use of anastrozole are not specific for this condition. They assess changes in the oral cavity as a whole and do not determine in what treatment phase it is more frequently found [2,6,10].
In the specific case of estrogen receptors, studies have evidenced that the presence of this hormone in the oral mucosa and salivary glands, as well as an antagonist action to this hormone, may be responsible for the sensation of dry mouth [2,11,12]. Preliminary results of a pilot study performed by Taichman et al. [2] did not show differences between the perception of dry mouth or decreased salivary flow of patients using aromatase inhibitors and patients without the medication. However, a longitudinal study performed by the same authors [12], published in 2016, warns about the long-term decrease in salivary flow due to the use of aromatase inhibitors, highlighting that further studies should be performed aiming at these patients with a higher need for oral health care.
Therefore, this research hypothesizes that anastrozole and bicalutamide used in the treatment of breast and prostate cancers, respectively, cause changes in salivary flow and the presence of xerostomia. This study aimed to assess the relationship of xerostomia and hyposalivation with the use of hormone therapy drugs in patients subjected to oncological treatment, by measuring salivary flow.