Improving the Quality of Cancer Registry Data on Adult Haematopoietic Neoplasms: Impact of Engaging Clinicians.

Haematological malignancies (HM) accounts for 7% of all cancers in England (DoH, 2003). However, concerns have been expressed regarding the quality of information from cancer registries (DoH, 2000, Haward, 2003) which sheds doubt on the validity of the data. Several initiatives have been undertaken to improve the quality of data (Cartwright et al., 1990, 1997, Clough et al., 1996, Taylor et al., 1998, Maynadie et al., 1996, Ong et al., 1997). These initiatives have been restricted in the range of diagnoses or have operated independently of national cancer registries (Phekoo et al., 2002). No studies have assessed the impact of incidence on survival rates. We present results of a collaboration designed to improve the quality of data and assess the impact on incidence and survival.

A consensus dataset and database of HM was developed between the Thames Cancer Registry (TCR) and clinicians between 1999 and 2000 in South Thames (adult population 5.4 million). Clinicians identified and confirmed the diagnosis of patients whilst diagnostic data were collected by a dedicated team of data collectors. Clinicians validated their cases bi-annually. Incidence and survival of the study population for the period 1999–2000 following the collaboration were compared with the same population over the period 1994–1996 prior to the collaboration and with a control population (North Thames area, adult population 5.5 million), where TCR collected data but without any clinical collaboration, for the period 1999–2000.

Statistical analyses: the statistical significance of the standardized rate ratio (SRR) was evaluated using the method of Jensen et al., (1991). The Kaplan-Meier survival curves were compared using the log-rank test.

For the period 1994–1996 there were no differences in the SRR or survival estimates in any disorders between North and South Thames. A 43% increase in incidence occurred between 1994–1996 and 1999–2000 in South Thames compared to only 5% in North Thames over the same periods, mainly for CLL, MDS, PV, PT, IMF, MGUS and WM. Table I shows a statistically significant difference in the SRR between the North and South Thames during the period 1999–2000 for five conditions: CLL, MDS, PV, PT and WM. Three year survival for patients diagnosed between 1999 and 2000 were higher in South Thames than North Thames in four conditions: CLL (71% vs. 49%, p = 0.001), CML (50% vs. 30%, p = 0.001), MDS (45% vs. 27%, p <0.001) and MM (39% vs. 28%, p <0.001). No significant difference in incidence or survival were seen for acute leukaemia, NHL or HD.

Table 1: Comparison of the age standardized rate between 1994–1996 and 1999–2000 in patients aged 16–85+ years

This study has shown that engaging clinicians have improved case ascertainment and that changes in incidence alone may affect outcome without significant differences in treatment. This study provides a benchmark of incidence and survival in the UK and a model for future collaborations.