The clinical course of recurrent respiratory papillomatosis after the use of cidofovir is influenced by multiple factors.

Abstract

With great interest we read the article of Grasso et al. [1] on the use of cidofovir in treatment of recurrent respiratory papillomatosis (RRP). The article discusses the positive influence regarding the number of interventions needed to eradicate papillomas after repeated administration of cidofovir. Although we have applied cidofovir for many years [2] and its long-term safety has been shown [3], we would like to emphasize that treatment effect of cidofovir should be handled with great care. In an article published online shortly after acceptation of the article of Grasso et al. we showed that the clinical course of RRP is influenced by multiple factors [4]. Changes in the clinical course of RRP should therefore only be considered as true treatment effect if these factors are taken into consideration or are corrected for. The natural clinical course of RRP shows a decrease of aggressiveness trough the course of the disease [4]. Furthermore, age of onset of the disease in combination with the HPV type (HPV6 or HPV11) are of great importance for the course of the disease [4]. The younger the age of onset, the worse the clinical course of the disease will be [4]. Especially younger HPV11 patients experience a more aggressive clinical course in comparison with their HPV6 peers [4]. Gastroesophageal reflux disease and asthma negatively influence the course of RRP [4]. In our opinion, it is advisable to not use the term ‘cure’ or talk of ‘remission’ when the follow-up of patients is only 1-month, as is done in some of the presented patients [1]. In our series of 55 patients it was shown that the disease can recur after 1 week till 34 years after the last surgical intervention [4]. Unfortunately, Grasso et al. [1] fail to give information on duration of the disease before administration of cidofovir, the age of onset, HPV type of all patients, and comorbidity. The true effect of cidofovir is therefore indeterminable. Concluding, it is of utmost importance that future research on treatment effect of any therapy in RRP patients should take into account this multifactorial composition of disease course. All factors mentioned above should be reported and corrected for to protect patients against unnecessary interventions. A multi-institutional randomized controlled trial should be considered to proof the effectiveness of cidofovir.