| Popis: |
The aim of this thesis was to examine modifiable risk factors that may influence cancer survival in colorectal and breast cancer patients, focusing on investigations of pharmacological exposures as well as smoking. While there is extensive evidence of the effects of smoking on cancer incidence, less is known of the effects of continued smoking after a cancer diagnosis on survival. A systematic review and meta-analysis conducted as part of this thesis, identified 20 studies that assessed the impact of smoking on colorectal cancer survival. Overall, this study found that smoking after a colorectal cancer diagnosis reduced colorectal cancer-specific mortality and disease-free survival, as well as overall survival. With a growing number of cancer survivors, many of whom are older and are regular users of common medications for co-morbidities, the exploration of possible effects of these medications on cancer outcomes is of particular importance. A growing body of evidence, both pre-clinical and epidemiological, suggests a role for many medications commonly prescribed in the general practice setting in cancer progression. Utilising linked data sources from United Kingdom cancer registries and the Clinical Practice Research Datalink, a number of medications were investigated in colorectal and/or breast cancer patients, including beta-blockers, ACEls/ARBs, statins, bisphosphonates and clopidogrel. The findings from this thesis suggest that there should be increased efforts in the clinical setting to support smoking cessation among CRC patients. While pharmacological studies largely revealed null results, reassuringly they suggest both ARB's and clopidogrel are safe for use in cancer patients. The protective associations on cancer mortality observed with statin use require confirmation in large, observational studies before randomised controlled trials of statin use in the adjuvant setting can be recommended. As all the drugs investigated in this thesis are generally well tolerated and the frequency with which they are prescribed, further research in this area is warranted. |
