title: Predictive characteristics of malignant pheochromocytoma.
abstract: OBJECTIVE
  The prognosis of patients with malignant pheochromocytoma is poor, but the predictive factors are not well understood. We aimed to identify the clinical characteristics predictive of malignancy after initial surgical removal in patients with pheochromocytoma.
  
  
  METHODS
  We retrospectively reviewed the records of 152 patients diagnosed with pheochromocytoma, including 5 (3.3%) with metastasis at the time of the initial surgical excision and 12 (7.9%) who developed metastasis during follow-up. To determine the factors predictive of malignancy, we compared clinical, radiographical, and urinary chemical findings between patients with benign and malignant disease. Mean follow-up was 41.5 months (range, 0.9-298 months) after surgery.
  
  
  RESULTS
  Malignant tumors were significantly larger than benign tumors (11.1±4.0 cm vs. 6.2±3.4 cm, p<0.001), and postoperative persistence of arterial hypertension was more frequent after removal of malignant than benign tumors (p=0.001). Among the 147 patients without metastatic disease at diagnosis, those who developed metastasis had significantly lower concentrations of urinary catecholamine metabolites per unit of tumor, including vanillylmandelic acid (1.2 vs. 3.7 mg/day/cm, p=0.049), epinephrine (4.5 vs. 168.9 µg/day/cm, p=0.008), and norepinephrine (13.1 vs. 121.8 mg/day/cm, p<0.001). The overall 5-year metastasis-free survival rate was 84.4% and was significantly higher in patients with smaller tumors (≤5.5 vs. >5.5 cm; 90.6% vs. 81.2%, p=0.025) and higher 24-hour secretion of vanillylmandelic acid (>2.1 vs. ≤2.1 mg/day/cm; 94.9% vs. 70.9%, p=0.019).
  
  
  CONCLUSIONS
  Large tumor size (>5.5 cm) and minimally elevated 24-hour urinary vanillylmandelic acid (≤2.1 mg/day/cm) were significantly associated with a higher probability of a malignant pheochromocytoma portending a lower metastasis-free survival and mandating more rigorous follow-up after surgery.
authors.affiliation: Department of Urology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Junsoo
authors.initials: J
authors.lastname: Park
authors.forename: Cheryn
authors.initials: C
authors.lastname: Song
authors.forename: Myungchan
authors.initials: M
authors.lastname: Park
authors.forename: Sangjun
authors.initials: S
authors.lastname: Yoo
authors.forename: Se Jun
authors.initials: SJ
authors.lastname: Park
authors.forename: Seokjun
authors.initials: S
authors.lastname: Hong
authors.forename: Bumsik
authors.initials: B
authors.lastname: Hong
authors.forename: Choung-Soo
authors.initials: CS
authors.lastname: Kim
authors.forename: Hanjong
authors.initials: H
authors.lastname: Ahn