Prognostic value of miliary versus non-miliary sub-staging in advanced ovarian cancer

- High-stage ovarian cancers commonly present with miliary disease.
- Miliary disease may be underemphasized by size and location based staging systems.
- Accounting for staging, cases with miliary spread are more likely to recur and have shorter survival.

ObjectiveThe presence of miliary disease during initial ovarian cancer debulking may reflect a distinct mode of peritoneal spread independent from size-based tumor staging and may explain variation in response to treatment and survival outcomes. To infer the prevalence, presentation and clinical implications of miliary disease we reviewed existing surgical records.MethodsReports were available for 1008 primary debulking surgeries for ovarian, primary peritoneal or fallopian tube cancer between 2001 and 2015 (685 reports from 2005 to 2015). Clinical outcome data was available for 938 patients. We analyzed a high-stage sub-cohort for survival (N = 436).ResultsMost records were evaluable for miliary disease (761/938); for these, the miliary phenotype was highly prevalent (249/761, 32.7%) and often accompanied by ascites (185/249, 74%). While optimal debulking rates were unaffected by miliary disease, total resection (R0) rates were poorer. Liver, stomach, spleen or bladder appeared to be sporadically involved while the omentum, mesentery, bowel, peritoneum and diaphragm were affected simultaneously (Spearman rho > 0.5). Overall, miliary disease was associated with worse progression free survival, overall survival, and time from relapse to death independent of stage. Survival effects were particularly strong for Stage IV disease where median overall survival varied by over 30 months (log-rank p = 0.002).ConclusionsMiliary disease is an identifiable surgical phenotype reflecting a distinct clinical trajectory that adds prognostic information to standard disease burden-based staging. These findings should permit further retrospective investigation in a wider cohort and prompt the consideration of prospective structured operative reporting standards and treatment strategies.