Surgical treatment of atypical metastasis from renal cell carcinoma (RCC).

Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? The interest in metastatic renal cell carcinoma has increased in the last few years, mainly due to the advent of targeted therapies, but metastasectomy remains the sole therapy that can lead to a complete and durable regression, even if only in a minority of patients. The literature reports quite large series of metastasectomies for the most common sites of metastasis, e.g. lung, liver, bone, adrenal and brain, whereas little is known about the management of metastasis in 'atypical' sites. The prognosis of patients submitted to metastasectomy for a metastasis in an atypical site is equivalent to patients with lung metastasis. The characteristics of the primary tumour in these patients are not indicative, but atypical metastasis (AM) are often located in superficial sites and frequently associated with other metastases. So, physical examination should be included in all follow-up regimens and a complete re-staging should be performed after the diagnosis of an AM. OBJECTIVE: •  To review the clinical characteristics and oncological results in patients submitted to surgical removal of metastasis from renal cell carcinoma (RCC) in atypical sites (atypical metastasis [AM], i.e. metastasis in sites other than the chest, liver, bone, adrenal, brain, kidney, and lymph nodes), compared with patients submitted to metastasectomy due to a lung metastasis (LM). PATIENTS AND METHODS: •  From an institutional database of ≈1800 patients surgically treated for a RCC, we retrospectively identified 37 cases that had undergone metastasectomy for AM and 57 operated for LM. •  Clinicopathological features of the primary RCC and metastasis, and cancer-specific survival (CSS) computed from the time of metastasectomy of patients with AM and LM, were compared. •  A univariate and multivariable analysis applying a Cox regression model was used to evaluate CSS. RESULTS: •  The patients with AM and LM were followed for an average of 40.8 and 50.7 months from metastasectomy, respectively (P= 0.372). •  There were no significant differences in the characteristics of the primary tumour between patients with AM and LM. •  In the cases with AM and LM the diagnosis was simultaneous with that of the primary tumour in 32.4\% and 24.6\%, (P= 0.40) respectively, and, when metachronous, occurred at an average delay of 53.4 and 44.3 months (P= 0.370). •  More frequently in the cases with AM other metastases had been diagnosed in the previous medical history (35.2 vs 8.8\%, P= 0.001) or simultaneously (48.6 vs 8.8\%, P= 0.001). •  CSS from metastasectomy was affected by the synchronicity in diagnosis between metastasis and primary tumour, and by the simultaneous presence of other metastases, while the type of metastasis (AM vs LM) did not affect CSS. In fact, metastasectomy in AM was as effective as in LM. CONCLUSION: •  AM are an exceptional presentation of metastatic RCC, but the role of surgery is similar to that of pulmonary metastasis. In these cases, metastasectomy is accepted as possible care, and in AM the CSS after metastasectomy is similar.