At present, only a single-center study and a SEER database based to assess the impact of organ-specific metastasis on the outcome of patients with systemic recurrence after local UTUC treatment[9, 10]. Since there are few studies in this direction, we doubled the sample size for further verification.
In this study, multivariate Cox regression showed that IVR, tumor size, and pT-stage played the role of independent predictors of metastatic disease recurrence after high grade UTUC after RNU. At the same time, it was found that that the liver, bone and multiple site recurrence of patients with UTUC seemed to be related to with rapid onset and poor prognosis. Also, the multiple site recurrence of UTUC patients combined with several sites had the fastest onset and worst prognosis. Lymph node, brain and lung recurrence had a longer onset and better prognosis when compared with other sites. As some previous studies have concluded, analysis of clinical and pathological features suggested that tumor size and pathological stage can predict recurrence. Evidence has shown that IVR was one of the strongest predictors of metastatic recurrence after RNU. Studies have shown that postoperative prevention of IVR by RNU may reduce the progression rate of muscle-invasive bladder cancer, thus improving the prognosis of patients with UTUC. Studies have shown that postoperative prevention of IVR by RNU may reduce the progression rate of muscle-invasive bladder cancer, thus improving the prognosis of patients with UTUC.
It is worth mentioning that, based on our data, LVI did not affect the recurrence of metastatic disease after RNU. However, LVI has been shown to be relevant to poor CSS in UTUC. Also, LVI was not evaluated in a population-based study. The type of surgery was irrelevant to the recurrence of UTUC patients after RNU, even though studies have shown that minimally invasive surgery was superior to open surgery in terms of the prognosis of urinary tract tumors.
The role of the site of organ metastasis in predicting patient survival has been gradually revealed in prostate cancer, renal cell carcinoma, and bladder urothelial carcinoma and other many types of cancer. Liver and bone recurrence has something to do with poor prognosis for a variety of tumors, such as metastatic renal cell carcinoma urothelial, carcinoma of the bladder. Bone recurrence showed a poor prognosis in breast cancer, and liver recurrence has a poor prognosis in colorectal cancer. Studies have shown that rapid recurrence of UTUC after RNU, in general, has something to do with poorer prognosis, similar to what we found in UTUC. In addition, it has been found that brain recurrence was subtler than other recurrence sites, lymph node recurrence have a higher survival rate, and they may be associated with a relatively better prognosis.
Currently, the therapeutic effects of UTUC metastasis sites are unknown, and details about chemotherapy, radiotherapy, and targeted therapies are lacking. However, different site-specific prognoses suggest that different sites of metastasis may respond in different ways to treatment.
It is believed that UTUC has a relatively low risk of recurrence in lung, brain and lymph nodes and intensive treatment strategies may improve the prognosis, while active treatment for liver, bone and multi-site metastases may have limited benefits for patients. The present study suggests a tendency that the location of organ metastasis in UTUC may influence the outcome of patients with relapse even though it’s not necessarily appropriate to guide clinical treatment decisions. Hence, these findings need to be supported by genetics. Exploring genetic association of recurrence sites of UTUC and the factors determining metastasis at specific sites may also be a great help. Unearthing these underlying mechanisms may help identify targets and treatment options that are beneficial to patients.
Our study has several limitations. First, the present study is a retrospective one with a sample from a single institution, prone to selection bias. Second, it lacks standardization of the remedial systemic care patients receive (often the physician empirically decides on chemotherapy, immunotherapy, or radiation). Third, surgical techniques vary from patient to patient. (we did not select patients from the same group of physicians because of the rarity of UTUC) Nevertheless, this is one of the largest single-center studies to investigate the effect of organ-specific metastasis on the outcome of UTUC in the presence of the rarity of UTUC. In the future, collaboration between multi-institutional research teams will be particularly crucial in order to better understand this phenomenon.