Re: JSLS. 2009;13(2):203-206 Laparoscopic mucin removal in patients with pseudomyxoma peritonei.

Dear Dr Michael S. Kavic:

This letter is regarding an article that appeared in Laparoscopic mucin removal in patients with pseudomyxoma peritonei. JSLS. 2009;13(2):203-206 by Kotani Y et al. from the Department of Obstetrics and Gynecology, Kinki University School of Medicine, Osaka-sayama, Osaka, Japan.

I write to you as a former patient of Pseudomyxoma Peritonei (PMP) and a member of many patient/research support organization for this disease and other peritoneal surface malignancies. The standard of care for PMP is cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). The efficacy and superiority of this treatment have been established by many studies across the world compared with serial debulking. The outcome of this treatment has shown survival rates of 85% in 20 year, according to the latest follow-up studies. At least 2 randomized trials and many multicentric studies support this claim. It has shown so much promise for PMP that it is now being extended to patients with peritoneal carcinomatosis from colon, gastric and ovarian cancer. The latest development in PMP is heading towards a more proactive and preventive outlook. It has been established that with this disease, minimally invasive procedures could only be justified for terminal cases.

The article in question makes largely false claims about the outcome of the standard treatment for PMP and clearly ignores the most relevant studies available today. Where recent studies have been cited, information from these studies was selected with deliberate bias to fit a dubious conclusion. Furthermore, there is a clear confusion between the studies on serial debulking, and those on cytoreductive surgery with HIPEC. The authors seem to use the unacceptable outcomes of the earlier to dismiss the latter. Sweeping claims about the disease's pathology were made without care for important details.

On the more specific methodological aspect of this study, the series of patients is too small to warrant any conclusions. Yet the authors allow themselves to conclude that laparoscopic removal of mucin may be better than surgical intervention. It is important to note that the series in support of the superiority of CRS and HIPEC include as many as 700 patients at a time. But trouble does not stop there; the authors entirely ignore the relevant articles on the limited use of laparoscopy for staging of PMP and exploration of peritoneal dissemination, which is at the core of the article's conclusion.

In my field as a patient and research advocate, we work very hard to educate both patients and healthcare practitioners on the life-saving value of cytoreductive surgery and HIPEC. I find it entirely disappointing that a reputable journal like JSLS would allow publications like this one to contribute to confusion and ignorance. The article lacks the basic requirements of scientific credibility that I found it imperative that I bring this matter to your attention and the attention of your editorial staff.

Best regards,

Dear Dr Kavic:

Thank you very much for granting us an opportunity to respond to the letter from Dr Amani Albedah, Director of Kuwait Group for Peritoneal Surface Malignancy, regarding our paper. We would like to supplement our article with the following information. We hope that our explanation will be acceptable and convincing to Dr Amani Albedah.

Pseudomyxoma peritonei (PMP) is a rare disease that is characterized by the collection of a large amount of mucinous material in the abdominal cavity, whether benign or malignant.

The accepted treatment methods for PMP include cytoreduction surgery and intraperitoneal chemotherapy,[1,2] but their superiority as initial therapy or in cases with repeated recurrences has not been verified in randomized controlled trials (RCTs).

Pathologically, PMP is benign or malignant. In malignant PMP, cytoreduction surgery and chemotherapy have been shown to be useful. All of the PMP cases that we managed were benign. Recently, PMP with benign tumors have been referred to as disseminated peritoneal adenomucinosis (DPAM).[2] It has been reported that cytoreduction surgery and intraperitoneal chemotherapy improve survival of patients with DPAM,[3] but the studies were not RCTs with a high level of evidence. There are no reports that show clear evidence for the treatment of PMP with benign tumors.

We accept the use of cytoreduction surgery and chemotherapy as initial therapy for PMP. For cases that have residual lesions and repeat recurrences, there is no useful treatment method that can significantly improve the prognosis. For patients who have a poor prognosis and repeat recurrences, repeat laparotomy is highly invasive. Thus, we performed laparoscopic mucin removal for patients with benign PMP with repeat recurrences. As a minimally invasive procedure, laparoscopy can be performed repeatedly, and can be used to remove mucin throughout the abdominal cavity by changing the position of the trocar.

We consider that laparoscopic surgery for PMP may not significantly improve the prognosis but is useful as a means to relieve symptoms.

Very respectfully,