Oesophageal cancer : on surgery and aetiology

Abstract

Oesophageal cancer is a common type of cancer with a dire prognosis. It is globally the eight most frequent malignancy and the sixth leading cause of death from cancer. The doctoral research described in this thesis has addressed the surgical treatment of oesophageal cancer from a morbidity perspective. It also provides some insight into the enigmatic male predominance of the most rapidly increasing subtype of oesophageal cancer, namely adenocarcinoma.

In the first study, the association between surgical factors and health-related quality of life was evaluated on the basis of data from a nationwide surgical register, comprising 355 surgically treated patients. A clinically relevant, statistically significant deterioration in several aspects of functioning and symptoms 6 months after surgery was shown in patients suffering from postoperative surgical complications.

The second study was based on same research register with the same patients and concerned the relation of hospital and surgeon volume to health-related quality of life 6 months after surgery. No influence of surgical volume on the patients functioning and symptoms was discerned.

In the third study the same surgical register was again used, but virtually all the patients who underwent oesophageal resection for cancer in Sweden from 2001 to 2005, inclusive, were involved. This prospective cohort study of 615 patients addressed the relationship between surgeon volume and postoperative surgical complications within 30 days. Surgeon volume had no discernible effect on the risk of surgical complications. Individual high-volume surgeons proved to have greatly differing results.

The fourth study was based on data from the Swedish Cancer Register and the Total Population Register. In this retrospective study the age-dependency of the incidence ratio of male to female gastrointestinal adenocarcinoma was evaluated. The sex ratio in oesophageal adenocarcinoma proved to be strikingly age-dependent, with point estimates of 8-10:1 in the younger age groups and about 4:1 in the older ones. This decline seemed to be steady and not related to the time of menopause in women, thus questioning the potential influence of oestrogen on the development of oesophageal adenocarcinoma.

The fifth and last study was based on a randomly selected sample from the adult Swedish population, comprising 4906 participants. This cross-sectional study strove to investigate the sex distribution of the established risk factors for oesophageal adenocarcinoma in the general population. Individual risk factors such as high BMI, tobacco smoking, and non-use of NSAIDs were overrepresented in men, while gastro-oesophageal reflux was more prevalent in women. No apparent clustering of risk factors was observed in men, and differences in separate risk factor exposure were small.