Colorectal Cancer Treatment and Survival: the Experience of Major Public Hospitals in South Australia over three Decades

Background: Registry data from four major public hospitals indicate trends in clinical care and survivalfrom colorectal cancer over three decades, from 1980 to 2010. Materials and
Methods: Kaplan-Meier productlimitestimates and Cox proportional hazards models were used to investigate disease-specific survival andmultiple logistic regression analyses to explore first-round treatment trends.
Results: Five-year survivalsincreased from 48% for 1980-1986 to 63% for 2005-2010 diagnoses. Survival increases applied to each ACPSstage (Australian Clinico-Pathological Stage), and particularly stage C (an increase from 38% to 68%). Risk ofdeath from colorectal cancer halved (hazards ratio: 0.50 (0.45, 0.56)) over the study period after adjusting forage, sex, stage, differentiation, primary sub-site, health administrative region, and measures of socioeconomicstatus and geographic remoteness. Decreases in stage were not observed. Survivals did not vary by sex or placeof residence, suggesting reasonable equity in service access and outcomes. Of staged cases, 91% were treatedsurgically with lower surgical rates for older ages and more advanced stage. Proportions of surgical cases havingadjuvant therapy during primary courses of treatment increased for all stages and were highest for stage C (anincrease from 5% in 1980-1986 to 63% for 2005-2010). Radiotherapy was more common for rectal than coloniccases. Proportions of rectal cases receiving radiotherapy increased, particularly for stage C where the increasewas from 8% in 1980-1986 to 60% in 2005-2010. The percentage of stage C colorectal cases less than 70 yearsof age having systemic therapy as part of their first treatment round increased from 3% in 1980-1986 to 81%by 1995-2010. Based on survey data on uptake of adjuvant therapy among those offered this care, it is likelythat all these younger patients were offered systemic treatment.
Conclusions: We conclude that pronouncedincreases in survivals from colorectal cancer have occurred at major public hospitals in South Australia dueto increases in stage-specific survivals. Use of adjuvant therapies has increased and the patterns of changeaccord with clinical guideline recommendations. Reasons for sub-optimal use of radiotherapy for rectal caseswarrant further investigation, including the potential for limited rural access to impede uptake of treatmentsat metropolitan-based radiotherapy centres.