Most Common Metastatic Sites and Routes of Spread in Ovarian Cancer
Ovarian cancer spreads primarily via transcoelomic (peritoneal) dissemination, with the most common metastatic sites being the peritoneum, omentum, diaphragm, and pelvic structures, while lymphatic spread to retroperitoneal nodes occurs in over 50% of cases and hematogenous metastasis is the least common route.
Primary Routes of Metastatic Spread
Transcoelomic (Peritoneal) Spread - Most Common Route
Transcoelomic metastasis is the predominant mechanism of dissemination and is responsible for the greatest morbidity and mortality in ovarian cancer. 1, 2
The most common sites of intraperitoneal seeding include: 3
- Pelvis (pelvic peritoneum, uterus, fallopian tubes)
- Omentum (frequently involved)
- Paracolic gutters
- Liver capsule (superficial metastases)
- Diaphragm (particularly right hemidiaphragm)
- Small bowel and mesentery
The disease spreads by direct extension, exfoliation of tumor cells into the peritoneal space, and dissemination along peritoneal fluid flow pathways. 3 Peritoneal involvement is present in approximately 70% of patients at initial diagnosis. 3
Lymphatic Spread - Second Most Common Route
Ovarian cancer spreads via lymphatics directly to pelvic nodes, para-aortic nodes, or both simultaneously with peritoneal dissemination. 4
Lymph node involvement rates: 4
- Pelvic lymph nodes: Positive in 57.9% of all stages (70.4% in Stage III)
- Para-aortic lymph nodes: Positive in 50.9% overall (67.6% in Stage III)
- Concomitant involvement: 40.4% of patients with positive pelvic nodes also have positive para-aortic nodes
- Skip metastases: 10.5% have positive para-aortic nodes with negative pelvic nodes
There is significant association between diaphragmatic involvement and retroperitoneal node metastases—84.4% of patients with diaphragmatic deposits also have positive retroperitoneal nodes. 4 This demonstrates that ovarian cancer spreads almost simultaneously via both intra-abdominal and retroperitoneal routes. 4
Hematogenous Spread - Least Common Route
Hematogenous metastasis occurs but is substantially less common than transcoelomic or lymphatic spread. 1, 2, 5
Distant hematogenous metastases (Stage IV disease) include: 6
- Parenchymal liver metastases (as opposed to capsular involvement, which is Stage III)
- Lung parenchyma
- Extra-abdominal organs
- Pleural effusion with positive cytology (Stage IVA)
- Inguinal lymph nodes and lymph nodes outside the abdominal cavity (Stage IVB)
Recent evidence has identified hematogenous metastasis to the omentum via circulating tumor cells, challenging the traditional view that all omental metastases occur via passive peritoneal fluid transport. 5
Staging Implications Based on Metastatic Sites
Stage III disease (most common at diagnosis) includes: 6
- Peritoneal implants outside the pelvis
- Positive retroperitoneal lymph nodes
- Superficial liver metastases (capsular involvement)
- Extension to liver or spleen capsule without parenchymal involvement
Stage IV disease includes: 6
- Parenchymal liver or splenic metastases
- Extra-abdominal metastases
- Pleural effusion with positive cytology
Clinical Implications for Surgical Staging
Comprehensive surgical staging must address both intra-abdominal and retroperitoneal spread patterns. 4 Required staging procedures include: 6
- Biopsy of diaphragmatic peritoneum
- Paracolic gutter biopsies
- Pelvic peritoneum assessment
- Complete pelvic and para-aortic lymphadenectomy (critical given high nodal involvement rates)
- Infracolic omentectomy
- Peritoneal washings from all four quadrants
- Appendectomy for mucinous tumors (8% have appendiceal involvement) 7
Common pitfall: Up to 31% of apparent early-stage ovarian cancers are upstaged with proper surgical staging, with the most common sites of occult disease being pelvic peritoneum, ascites, para-aortic nodes, and diaphragm. 6