Comparing survival outcomes for patients with colorectal cancer treated in public and private hospitals

To the Editor: We suggest that marked differences in comorbidities could be one explanation for the superior outcomes for patients with colorectal cancer treated in private hospitals as reported in the study by Morris et al.1 We also have concerns about the quality of the data used in their study.

We used a comprehensive prospective database to examine a cohort of Victorian patients treated at the Royal Melbourne Hospital (n = 260) and the adjacent Melbourne Private Hospital (n = 118) between 2003 and 2006. Specifically, we included data on important patient variables that were not considered in the Western Australian series (Box). These data showed a clear bias towards improved postoperative and long-term survival outcomes for patients in the private system, independent of cancer treatment. Significantly, diabetes, which affected a much larger proportion of public than private hospital patients, is also associated with inferior cancer-specific outcomes.2 Together, these results could explain the differences reported by Morris et al. In support of this, the 5-year cancer-specific survival rates they report for stage I cancer in the two hospital groups is similar (89% public versus 92% private), but the overall survival rates are markedly different (74% public versus 85% private) — consistent, we contend, with an excess of non-cancer deaths in public patients.

Morris et al also report an imbalance in the receipt of adjuvant chemotherapy between public and private patients, possibly a marker of inequality of care. We analysed prospectively collected data for our patients with stage III colon cancer, where adjuvant chemotherapy has a proven impact on survival. As shown in the Box, a similar percentage were offered, accepted and completed adjuvant chemotherapy, suggesting, in Victoria at least, similar access to care and support for public and private patients.

The pathology-based staging used by Morris et al may also be inaccurate, as recording of stage IV disease relies on the surgeon noting this on the pathology request form and patients having been fully evaluated before surgery (we contend that preoperative computed tomography scanning would not have been routine). This may explain the relatively low percentage of patients recorded as having stage IV disease (12% public; 9% private) compared with 17% in our combined series in which prospective clinicopathological staging was used.

Finally, inaccurate data are suggested by the reported 5-year overall survival figures for patients with stage IV cancer (17% in private care).1 That this is superior to figures reported in recent clinical trials is an unexpected finding, particularly as clinical trials enrol only a select subset of patients and provide access to novel combination chemotherapy, and presentation with metastatic disease is an adverse prognostic factor.