DISCUSSION
RCC is the sixth most common malignant tumor in males and the tenth most
common malignant tumor in females[10]. RCC recurs after more than 10
years of nephrectomy in 10% of the cases[11]. The most common sites
of metastasis include lungs, bones, lymph nodes, adrenal glands, liver,
brain contralateral kidney, and pancreas[5]. Metastatic clear cell
RCC has a poor prognosis with a median overall survival of 12 months
only which has improved in the last decade[12]. Pulmonary metastasis
from RCC after a long interval is rare. This is the first case of lung
metastasis from renal cell carcinoma that we have encountered in our
institution. To our knowledge, this is the first case of lung metastasis
secondary to clear cell renal cell carcinoma reported from Nepal to
date.
Shiono et al. reported a case with repeated metastasectomy for lung
metastasis 16, 24, and 25 years after RCC treatment[7]. Shiono et
al. also reported a mini-review of 5 cases of RCC with lung metastasis
after 20-28 years of resection of primary neoplasm throughout
1973-1998[7]. Watanabe et al. reported pulmonary metastasectomy
after 10 years of nephrectomy. Left upper lobectomy was performed in an
82-year-old patient who was consequently disease-free at 9 months
follow-up[8]. Tamburrini et al. reported lung metastasis after 37
years of RCC resection. The patient had a central hilar mass which was
suspected as primary lung cancer but histological examination revealed
metastatic RCC. Left pneumonectomy was performed in this patient. The
patient was recurrence-free at 3 years follow-up[9]. Genand et al.
reported solitary lung metastasis in a patient 17 years after
nephrectomy for RCC[13].
Disease recurrence likelihood for RCC depends on several known and
unknown factors including host and tumor factors[5]. Prognostic
indicators for RCC include complete resection of all metastasis, low
number of metastasis, long disease-free interval between primary tumor
diagnosis and lung lesions, lymph node involvement, and size of
pulmonary nodule[9]. Host immune response has been hypothesized to
play a role to determine the time for the presentation of RCC
metastasis. Duration decreases with compromised immune response[9].
The five and 10-year overall survival rate following pulmonary
metastasectomy for metastatic renal cancer was 83% and 41.7%
respectively according to Chen et al. [14]and 75% and 59%
respectively according to
Meacciet
al.[15].