Discussion
Although various medicine and even HPV vaccines have been tried to be applied to adjuvant therapy for RRP, mainstay of treatment has largely been surgical, which has evolved from microdebrider and other cold instruments to include certain types of laser instruments over the past few decades.
Microdebrider is a dynamic rotational dissection device with suction assist, which has become the preferred treatment for handling JO-RRP in recent years. Microdebrider can easily push the mass away from the base and suck up, remove the mass accurately, cause it can easily reach the throat and trachea under the laryngoscope. Patel[12] noted in a retrospective study that the operation time was significantly shortened since the CO2 laser switched to microdebrider, with the advantages of saving surgical costs, avoiding the risk of airway burns that may occur during laser surgery and the possibility of vaporization of virus particles. Microdebrider may replace CO2 lasers, the preferred method of airway clearance in these patients, and become the surgical modality of choice for RRP in some institutions. In addition, microdebriders may be a more cost-effective tool for removing bulky diseases than lasers alone, that’s why it has become the main surgical modality to treat Jo-RRP. Go a step further, Huang[13] notes that the surgeons prefer to use microdebrider for bulky tumors and use KTP laser peeling technique for near-normal structure. This mixing mode can help surgeons shorten surgery time and make it easier to control bleeding, and it may avoid injury to the stratified structure of the vocal cords. Actually, microdebrider has some drawbacks. Hemostasis is an issue with cold techniques, but the surgical field of microdebrider could remains clear most of the time due to the suction of the connection[14].
CO2 laser was applied to the treatment of RRP as early as the early 1970s, which replaced the traditional cold instrument, and gradually become a recognized treatment method for laryngeal diseases. The wavelength of the CO2 laser (10 600 nm) is absorbed by water, allowing the lesion to evaporate with a high percentage of intracellular water[15]. However, CO2 laser operation is time-consuming, expensive, and potentially dangerous of airway burning. One of the most serious risk factors is airway combustion, normal tissue burns and medical staff damaged If the intraoperative procedure is improper.
Unlike the CO2 laser, the angiolytic laser uses the peak in the absorption spectrum of the oxygen hemoglobin rather than water, which helps to selectively ablate the vascularized lesion without excessive thermal damage. As a kind of the angiolytic laser, KTP laser seems has great advantages in RRP resection, due to the blood-rich nature of RRP[16]. In other words, the KTP laser can better preserve the surrounding tissue and hemostasis control. Huang[13] revealed that serial KTP laser procedures can effectively control RRP while preserving phonatory function and maintaining adequate voice quality through a longitudinal follow-up study. Burns[17] also demonstrated that diseases in the anterior commissure of glottis can be treated with minimal risk of scarring or adhesions, whether using KTP lasers alone or as a complement to other surgical modalities, with minimal preservation of the potential superficial intrinsic layer.
There have been few studies that directly compare the effects of different surgical modalities on RRP recurrence rates. The results of our study are consistent with these studies. Hock[16] analyzed the Derkay score improved between first and last procedure in group of three surgical modalities(KTP, CO2, and microdebrider), and found no significant difference among the three treatment groups. Preuss[18] suggested no correlation between the recurrence rate and surgical modalities. However, these studies lacked a unified indicator of effectiveness, and did not compare the three surgical modalities in Jo-RRP and Ao-RRP separately.
Patients with RRP often need to undergo repeated surgeries, which is a heavy financial burden. Medical institutions have started transferring the performance of some procedures from the operating room to the office, which would theoretically result in substantial savings. The flexible CO2 wave-guide laser has been developed and commercially available for several years, which can transfer surgery in the operating room to the office under local anesthesia[19]. A study of Ao-RRP case series concluded that office procedures are significantly more cost-effective than operating room procedures, but their use may be limited by patient tolerance and the increased frequency of the procedure[20].
In our study, treatment intervals and recurrence trends did not differ across three subgroups in both Jo-RRP and Ao-RRP patients, that is to say, three surgical modalities appeared to be equally effective in terms of controlling the recurrence of RRP. Therefore, the same recurrence rate control effect can be achieved using microdebrider for medical institutions without laser equipment. More attention should be paid to other factors such as the economic cost, availability and complications of surgery in decision-making of the surgical modality, which should be further investigated. In addition, Derkay score was used to grade the lesion anatomy to ensure the comparability between different groups, which was rarely used in previous reports. Studies in the future would require detailed reporting of disease burden, so that patients could be risk stratified by group. Pre-op and post-op Derkay scores or other consisten quantitative metrics are necessary, to accurately stage the bulk and severity of disease to allow for more standardized reporting of disease.
There are several limitations to this study. First, this is a retrospective cohort study, we couldn’t collect detailed case information in a completely random manner. Secondly, we did not investigate the outcome of complications because most patients may have undergone multiple surgeries. Future studies should conduct more randomized controlled tests and include postoperative complications in statistics to determine the best surgical modalities.