Pretreatment quality of life in patients with rectal cancer is associated with intrusive thoughts and sense of coherence

Rectal cancer is potentially life threatening. Curative treatment is attempted in about 80% while remaining patients receive palliative treatment [17]. Survival has improved in recent years, and consequently, quality of life (QoL) has received increasing attention [1]. Interestingly, several studies have found QoL to be predictive of survival in patients with cancer [9, 25, 31]. Furthermore, one study has demonstrated the prognostic significance of pretreatment QoL for survival in primary rectal cancer [8]. Several factors may influence pretreatment QoL in patients with newly diagnosed rectal cancer, including the cancer disease per se [12]. QoL could be influenced by the treatment plan, i.e., curative or palliative intent and the type of surgical procedure planned. Several studies have found QoL to be associated with psychological and personality trait variables independent of clinical factors [13, 27, 32, 33]. Cancer-related intrusive thoughts, i.e., unintentional recurrent or distressing thoughts about cancer, are among the more prominent stress-related symptoms experienced by patients with cancer [15, 30]. An association has been reported between intrusive thoughts and QoL in patients with prostate cancer [37, 41], but this has not been studied in patients with rectal cancer. Another psychological variable that may be associated with QoL is sense of coherence (SOC), which reflects a person’s view on life and capacity to respond to stressful situations [2, 10]. Sense of coherence was developed by Aaron Antonovsky in the 1970s [2] and may be regarded as a test of personality traits or coping disposition. It mirrors the extent to which we perceive life as comprehensible, manageable, and meaningful [24]. An association between sense of coherence and quality of life has been reported in several studies [10].

We hypothesized that pretreatment quality of life is influenced by psychological factors irrespective of clinical variables like intent of treatment. The primary objective of the present analysis was to investigate the association of intrusive thoughts and the patients’ sense of coherence with pretreatment quality of life in patients with newly diagnosed rectal cancer.

Between February 2012 and September 2015, 16 departments of surgery in Sweden and Denmark prospectively included 1248 patients with newly diagnosed rectal cancer, of which 1085 patients were available for analysis (Fig. 1). There were no significant differences regarding patient demographics between patients to be treated with curative or palliative intent (Table 1) or any clinically relevant differences regarding age, sex, or tumor height between these groups (Table 2), but as expected, the tumor stage differed. The distribution of sex, age, ASA grade, and clinical tumor stage differed significantly between patients included in the study and non-included patients (Table 3).

In the study group, intrusive thoughts were frequent among all patients without any significant differences between patients planned for curative and palliative treatment (Table 4). Sense of coherence differed slightly between groups (Table 4).

Patients planned for palliative treatment assessed their overall QoL and global health-related QoL as lower than patients with a curative treatment plan (Table 5). Patients with a curative treatment plan had similar global health-related QoL as a general population, but significantly lower overall QoL (data not shown). Patients planned for APE reported lower overall QoL, but not lower global health-related QoL, compared with patients planned for other types of curative treatment (Table 5). The experience of intrusive thoughts was associated with lower overall QoL and global health-related QoL. The higher the frequency and perceived intrusiveness of these thoughts, the greater was the impact on QoL (Table 5). A 25-unit increase in the total score of SOC-29 was associated with better overall QoL (odds ratio 0.44, 95% confidence interval 0.37–0.52), and sense of coherence was positively correlated with global health-related QoL (Spearman correlation 0.44; p < 0.001).

In the present study, we found that QoL was lower in patients planned for palliative compared with curative treatment. Patients with potentially curable disease had a global health-related QoL comparable to that of a general population, but a significantly lower overall QoL. It is important to note that low QoL was associated with the experience of intrusive thoughts, a possibly modifiable factor. QoL was also associated with sense of coherence, a personal trait factor.

The physical effects of the disease burden as well as the psychological reaction to the palliative situation may partly explain the low QoL in patients planned for palliative treatment. One such reaction is intrusive thoughts which may be modified by expressive writing, cognitive behavioral therapy, and pharmacological interventions [19, 23]. Although previously thought to be intrinsic and non-modifiable, recent preliminary data have indicated that sense of coherence may indeed be strengthened by psychotherapy [16].

There were no clinically relevant differences of overall QoL or global health-related QoL between patients planned for curative treatment with APE vs. other curative procedures [29]. In view of the fact that 97% of the curative patients felt well informed about their treatment, this indicates that patients received adequate supportive care when presented with their treatment plan, including patients scheduled for a permanent stoma. As recently reported, Swedish patients’ QoL was not limited by the presence of a permanent stoma following APE for rectal cancer [21].

A lower percentage of patients planned for palliative treatment considered themselves well informed about their diagnosis and treatment plan compared with patients planned for curative treatment. This indicates a need for improved communication of palliative treatment, perhaps in a more structured manner [28, 40]. In this context, better support for the surgeon may ultimately improve patient outcome [5].

QoL was assessed by two global single questions pertaining to “overall” and “health-related” QoL, respectively. While the latter question concerns the patients’ self-rated health state, the question on overall QoL relates also to other aspects of life that may affect QoL. In view of this, it is interesting that patients with a potentially curable disease differed from a normal population with regard to overall but not global health-related QoL, meaning that their “health state” was not impaired by the cancer but their general perception of QoL was.

Strengths of this study include the large patient cohort and the inclusion of patients regardless of tumor stage. The participation of university as well as county hospitals increases the generalizability of results. Study hypotheses and a detailed statistical analysis plan were decided on prior to data analyses. The questionnaire was developed in a systematic way using prevalidated questions as well as newly constructed disease-specific questions validated according to accepted principles [3, 6, 18, 36, 37]. The patients completed the questionnaire at home and returned it to the coordinating center and not to the treating hospital which may minimize bias [20].

Missing data were generally low. However, for global health-related QoL, missing and/or invalid values were more frequent, which we found to be partly explained by difficulties for patients to correctly interpret instructions on how to fill out their response on the EQ-5D-3L visual analogue scale. This may potentially bias the results, but the direction and significance of this bias are unclear.

Women were overrepresented among included compared to non-included patients, but the sex distribution in the study group was comparable to that reported for all new cases of colorectal cancer in Europe 2012 [39]. Median age differed significantly between included and non-included patients, but the 1-year difference is hardly of any clinical relevance in relation to QoL. Included patients had a significantly lower ASA grade, indicating that they were somewhat healthier than non-included patients. Clinical tumor stage was significantly lower in the study group. The differences in ASA grade and clinical tumor stage between included and non-included patients must be considered in relation to the generalizability of results, although the clinical relevance of the rather small differences is difficult to determine.

A good understanding of Swedish or Danish was required for participation, and thus, the results are not valid for patients with little or no knowledge of these languages. Another limitation of the study is that we did not have detailed information on how the treatment plan was communicated to patients. However, many participating departments of surgery and caregivers may reduce the influence of differences in communication and may reflect real life clinical practice at the time.

Although efforts were made to recruit palliative patients to the study, they seem somewhat underrepresented. However, the classification of patients as curative or palliative was done prospectively at the time of inclusion. As some patients initially scheduled for curative treatment were not operated, the number of missed palliative patients may actually not be as large as it looks. If a selection bias is present with regard to patients planned for palliative treatment, it may lead to an overestimation of QoL in this group.

Our results indicate that psychological factors need to be considered as confounders in clinical studies that aim to describe quality of life. Furthermore, reducing intrusive thoughts by way of a simple intervention like expressive writing [23] may offer patients relief and possibly improve quality of life in the face of a rectal cancer diagnosis.

The reported association of QoL and survival in patients with cancer in general [9, 25, 31], and of pretreatment QoL and survival in primary rectal cancer in particular [8], underpins the importance of our results. Furthermore, a survival benefit of psychosocial intervention in patients with cancer has been suggested [35]. However, whether efforts to improve pretreatment QoL will translate into a better survival in patients with rectal cancer remains to be demonstrated.

We conclude that the QoL of Scandinavian patients who had just received the treatment plan for their newly diagnosed rectal cancer may be influenced by the presence of intrusive thoughts and the patients’ sense of coherence as well as of the intent of treatment. Future studies should evaluate the effect of interventions aimed to improve QoL.