The Prevalence of Back Pain in Patients Operated on Due to Colorectal Cancer Depending on the Type of Surgical Procedure Performed

Simple Summary Our study aimed to assess back pain in patients undergoing surgery for colorectal cancer following anterior resection of rectum (AR), laparoscopic anterior resection of rectum (LAR), Hartmann’s procedure (HART), or abdominoperineal resection of rectum (APR). The studied patients were examined three times: prior to surgery (I), six months after surgery (II), and one year after surgery (III). The analysis of study results revealed that an increase in the degree of disability and functioning impairment occurred in all groups between time points I and II. A reduction in low back pain was observed one year after the procedure in the LAR group. Abstract Purpose: Low back pain presents a serious challenge for numerous medical specialties. The purpose of this study was to assess disability due to low back pain in patients operated on due to colorectal cancer depending on the type of surgery performed. Methods: This prospective observational study was carried out in the period of July 2019 through March 2020. Included in the study were patients with colorectal cancer for scheduled surgeries including anterior resection of rectum (AR), laparoscopic anterior resection of rectum (LAR), Hartmann’s procedure (HART), or abdominoperineal resection of rectum (APR). The Oswestry Low Back Pain Disability Questionnaire was used as the research tool. The study patients were surveyed at three time points: before surgery, six months after surgery, and one year after surgery. Results: The analysis of study results revealed that an increase in the degree of disability and functioning impairment occurred in all groups between time points I and II, with the differences being statistically significant (p < 0.05). The inter-group comparative analysis of the total Oswestry questionnaire scores revealed statistically significant differences, with the impairment of function being most severe within the APR group and least severe within the LAR group. Conclusion: The study results showed that low back pain contributes to impaired functioning of patients operated on due to colorectal cancer regardless of the type of procedure performed. A reduction in the degree of disability due to low back pain was observed one year after the procedure in patients having undergone LAR.


Introduction
Each year, about 18,000 new cases of colorectal cancer are diagnosed in Poland. The radical treatment of this cancer is based on surgical resection of the tumor. Depending on the tumor location and the stage of the disease, the surgical treatment may be supplemented by neoadjuvant or adjuvant radio-or chemotherapy [1]. The inclusion criteria were met by 163 patients. A total of 58 patients were lost to follow-up or refused further participation after the first time point while another 10 patients were lost to follow-up or refused further participation after the first time point. After the first stage of the study, 25 patients did not answer the phone or did not consent to further participation in the study. Finally, a total of 96 patients were included in the analysis.
The inclusion criteria were as follows: consent to participate in the study; -age over 18 years; -colorectal cancer patients qualified for scheduled surgeries including anterior resection of rectum, laparoscopic anterior resection of the rectum, Hartmann's procedure, or abdominoperineal resection of the rectum; -the primary character of colorectal cancer surgery; -good mobility, Zubrod-ECOG-WHO performance score of 0-1; -colorectal cancer of stage I-III as per preoperative assessment.
The exclusion criteria were as follows: disseminated disease (stage IV cancer); -ASA score of 4 or higher; -intraoperative conversion from laparoscopic to open surgery; -severe cardiovascular, pulmonary, orthopedic, and neurological pathologies; -cognitive impairment; -local recurrence or distant metastases in the follow-up period.
Patients meeting the inclusion criteria were given the opportunity to participate in the study. Having talked to the investigators and having read the patient information sheet, the participants signed the written informed consent forms. Next, the patients were asked to complete the Oswestry Disability Index questionnaire, also known as the The inclusion criteria were met by 163 patients. A total of 58 patients were lost to follow-up or refused further participation after the first time point while another 10 patients were lost to follow-up or refused further participation after the first time point. After the first stage of the study, 25 patients did not answer the phone or did not consent to further participation in the study. Finally, a total of 96 patients were included in the analysis.
The inclusion criteria were as follows: consent to participate in the study; -age over 18 years; -colorectal cancer patients qualified for scheduled surgeries including anterior resection of rectum, laparoscopic anterior resection of the rectum, Hartmann's procedure, or abdominoperineal resection of the rectum; -the primary character of colorectal cancer surgery; -good mobility, Zubrod-ECOG-WHO performance score of 0-1; -colorectal cancer of stage I-III as per preoperative assessment.
The exclusion criteria were as follows: disseminated disease (stage IV cancer); -ASA score of 4 or higher; -intraoperative conversion from laparoscopic to open surgery; -severe cardiovascular, pulmonary, orthopedic, and neurological pathologies; -cognitive impairment; -local recurrence or distant metastases in the follow-up period.
Patients meeting the inclusion criteria were given the opportunity to participate in the study. Having talked to the investigators and having read the patient information sheet, the participants signed the written informed consent forms. Next, the patients were asked to complete the Oswestry Disability Index questionnaire, also known as the Oswestry Low Back Pain Disability Questionnaire. The questionnaire contained 10 questions on pain intensity, personal care, lifting, walking, sitting, standing, sleeping, social life, travel, and pain intensity changes. Each question was accompanied by 6 optional answers scored 0 to 5 with higher scores corresponding to higher degrees of disability. The sum of the answers to the 10 questions amounted to a minimum of 0 points and a maximum of 50 (percentage range 0 to 100%). The disability levels were defined as follows: 0-20%-minimal disability; 21-40%-moderate disability; 41-60%-severe disability; 61-80%-crippled; 81-100%-complete motor impairment.
Clinical and sociodemographic data as available in the patients' records, such as age, weight, height, BMI, hospitalization time, gender, pre-and post-operative treatment, postoperative complications, and disease staging, were also used in the analysis.
The patients were surveyed at three time points: the first questionnaire was completed in the hospital prior to surgery while the second and third questionnaires were completed six months and one year after the procedure, respectively. The responses at the latter two time points were collected by means of the CATI-Computer Assisted Telephone The patients were interviewed by telephone due to the ongoing coronavirus pandemic. Patients, by signing informed consent, knew at what point in the procedure telephone contact would occur. The persons interviewing the patients were the 4 authors of the manuscript.
ERAS protocol was extensively followed at the study site. Prior to surgery, the attending physician recommended that the patients receive preoperative protein supplementation, physical activity was maintained before and after the procedure in the recovery, a carbohydrate-rich drink was administered up to 2 h prior to anesthesia, preoperative fasting was avoided, and timely restitution of oral nutrition following surgery was recommended. Attention was paid to reducing the dwelling times of abdominal drains and urinary catheters, avoiding routine use of gastric probes, and discharging hospitalized patients in a timely manner. Recommendations for home-based nutritional management were given out to patients upon discharge.

Statistical Methods
Statistical analyses were carried out using the PQStat statistical package version 1.8.2.232.
Inter-group differences in age, weight, height, and BMI were analyzed by means of the unifactorial analysis of variance and the post-hoc Tukey test whereas differences in hospitalization times were analyzed by means of the Kruskal-Wallis test with the post-hoc Dunn-Bonferroni's test.
For qualitative variables, such as gender, pTNM, pre-and post-operative management, complications, and disease staging, the chi-squared test or the exact Fisher's test was used.
The Oswestry questionnaire scores were compared between patient groups using the Kruskal-Wallis test while the differences between individual time points were analyzed using the Friedman test. The Dunn-Bonferroni test was used for post-hoc analysis in both cases.
The disability scales (%) between individual surgery groups were compared using the Kruskal-Wallis test. Pre-and post-operative scores were compared using the Friedman test.
A test probability of p < 0.05 was defined as statistically significant whereas a test probability of p < 0.01 was defined as highly significant.

Results
A total of 96 patients were included in the analysis, with 37 patients operated on by means of anterior resection of the rectum, 24 patients operated on by means of laparoscopic anterior resection of rectum, 13 patients operated on by means of Hartmann's procedure, and 22 patients operated on by means of abdominoperineal resection of the rectum.
The study groups did not differ in age, weight, height, BMI, or postoperative hospitalization times (p > 0.05). The characteristics of the study groups are presented in Table 1. APR-abdominoperineal resection of the rectum; AR-anterior resection of the rectum; LAR-laparoscopic anterior resection of the rectum; HART-Hartmann's procedure; p-statistical significance level. ** in the case of the "hospitalization time" variable, the analysis involved the Kruskal-Wallis test with the Dunn-Bonferroni post-hoc test.
The study groups were analyzed in terms of qualitative data. No statistically significant differences were observed between the study groups regarding the patients' gender, type of postoperative management, and disease staging (p > 0.05) whereas statistically significant differences were observed with regard to the type of preoperative management (p = 0.0072). The results are presented in Table 2. Table 2. Qualitative clinical data and inter-group differences in individual patient groups (abdominoperineal resection of the rectum, anterior resection of rectum, laparoscopic anterior resection of the rectum, and Hartmann's procedure). APR-abdominoperineal resection of the rectum; AR-anterior resection of the rectum; LAR-laparoscopic anterior resection of the rectum; HART-Hartmann's procedure; p-statistical significance level. Table 3 shows answers to the individual questions within the Oswestry questionnaire as provided in different study groups and at different study time points. Highly statistically significant differences were observed at different time points within each group with regard to pain intensity, personal care, lifting, walking, and sitting (p < 0.01); highly statistically significant differences were also observed at different time points with regard to standing within the LAR group (p = 0.0002), sleeping within the APR group, pain intensity changes in the APR, AR, and LAR groups (p < 0.01), travel in the APR group, and social life in the APR, AR, and LAR groups. Statistically significant differences were observed with regard to sleeping in the AR group. Table 3. Results in the individual subscales of the Oswestry questionnaire in individual groups (abdominoperineal resection of the rectum, anterior resection of rectum, laparoscopic anterior resection of rectum, and Hartmann's procedure) and at different study time points.   Presented in Table 3 are the overall results of the Oswestry questionnaire. No significant differences were observed between study groups at the first and the second time points. At the third time point, highly statistically significant differences were observed between the study groups. The highest scores translating to the highest levels of pain were recorded in the APR group. The lowest scores corresponding to the best functioning were reported in the LAR group.

Group
Listed below the median values are the letter codes indicating the homogeneity of groups as per the Dunn-Bonferroni test results. The first row below the median values provides the results of the Kruskal-Wallis test whereas the second row below the median values provides the results of the Friedman test.
At the next stage of the analysis, patients within the study groups (APR, AR, LAR, and HART) were assigned to appropriate disability levels. No statistically significant differences in the disability level were observed at the first and the second time points between groups operated on using different surgical approaches. The results are shown in Figures 2 and 3.  Cancers 2023, 15, x FOR PEER REVIEW 10 of 15  Statistically significant differences were observed with regard to the disability levels depending on the type of surgery (p< 0.01). The lowest scores translating to the lowest disability level were observed within the LAR group. The results are presented in Figure  4.  Statistically significant differences were observed with regard to the disability levels depending on the type of surgery (p< 0.01). The lowest scores translating to the lowest disability level were observed within the LAR group. The results are presented in Figure  4. Statistically significant differences were observed with regard to the disability levels depending on the type of surgery (p < 0.01). The lowest scores translating to the lowest disability level were observed within the LAR group. The results are presented in Figure 4. The next stage of the analysis consisted in analyzing the differences in disability levels depending on the study time point. A highly significant change (p <0.01), i.e., an increase in the disability level between time points I and II was observed in the group having undergone the APR. A highly significant change (p <0.01), i.e., an increase in the disability level between time points I and II was observed in the AR group. Highly significant changes (p <0.01), i.e., an increase in the disability level between time points I and II and a reduction in the disability level between time points II and III were observed in the LAR group. No significant differences (p< 0.05) were observed between individual time points in the HART group.

Discussion
The study results showed that low back pain is observed in patients operated on due to colorectal cancer regardless of the type of procedure performed. The greatest intensity of pain was observed six months after the surgical procedure. A reduction in low back pain was observed one year after the procedure in the LAR group. The highest levels of pain in the lumbar area were observed in patients having undergone the APR procedure.
According to our knowledge, this was the first study to evaluate the intensity of low back pain in patients operated on due to colorectal cancer depending on the type of surgery performed. Patient evaluation was carried out within a yearly time frame. The Oswestry questionnaire which had been successfully used in numerous previous studies [9][10][11], was used as the study tool.
The study showed that the intensity of pain was highest within the APR group. This was obviously due to the fact that APR was the most extensive of all analyzed procedures, involving a 15-20-cm incision being made within the medial line, sigmoidostomy being formed, and an additional perineal incision, 10-15 cm in length, being made to remove the sphincter apparatus [12].
The bowel movement pattern is also changed in ostomy patients. The lack of tenesmus upon defecation results in the inactivation of the muscles of the pelvic diaphragm, the abdomen, and the respiratory diaphragm. The dyssynergy of these muscle groups may lead to disturbed postural control and complications resulting from abnormal intraabdominal pressures; these, in turn, may either trigger or contribute to the ex- The next stage of the analysis consisted in analyzing the differences in disability levels depending on the study time point. A highly significant change (p < 0.01), i.e., an increase in the disability level between time points I and II was observed in the group having undergone the APR. A highly significant change (p < 0.01), i.e., an increase in the disability level between time points I and II was observed in the AR group. Highly significant changes (p < 0.01), i.e., an increase in the disability level between time points I and II and a reduction in the disability level between time points II and III were observed in the LAR group. No significant differences (p < 0.05) were observed between individual time points in the HART group.

Discussion
The study results showed that low back pain is observed in patients operated on due to colorectal cancer regardless of the type of procedure performed. The greatest intensity of pain was observed six months after the surgical procedure. A reduction in low back pain was observed one year after the procedure in the LAR group. The highest levels of pain in the lumbar area were observed in patients having undergone the APR procedure.
According to our knowledge, this was the first study to evaluate the intensity of low back pain in patients operated on due to colorectal cancer depending on the type of surgery performed. Patient evaluation was carried out within a yearly time frame. The Oswestry questionnaire which had been successfully used in numerous previous studies [9][10][11], was used as the study tool.
The study showed that the intensity of pain was highest within the APR group. This was obviously due to the fact that APR was the most extensive of all analyzed procedures, involving a 15-20-cm incision being made within the medial line, sigmoidostomy being formed, and an additional perineal incision, 10-15 cm in length, being made to remove the sphincter apparatus [12].
The bowel movement pattern is also changed in ostomy patients. The lack of tenesmus upon defecation results in the inactivation of the muscles of the pelvic diaphragm, the abdomen, and the respiratory diaphragm. The dyssynergy of these muscle groups may lead to disturbed postural control and complications resulting from abnormal intraabdominal pressures; these, in turn, may either trigger or contribute to the exacerbation of lower back pain. Unfortunately, no studies on the presented subject could be found in the available literature.
Other authors reported on cases of back pain in patients with ostomies [13,14]. In our study, ostomies were formed in patients having undergone Hartmann's procedure or abdominoperineal resection surgeries. No differences were observed with regard to the disability levels within the HART group, as well as no differences were observed within this group with regard to the Oswestry questionnaire subscales of standing, sleeping, social life, travel, and changes in the intensity of pain as well as to the total Oswestry scores. However, the group of patients having undergone Hartmann's procedure was less numerous than the other groups, which makes it difficult to interpret the results or draw any firm conclusions on the basis thereof.
An increase in back pain was observed in our study between time points I and II in the APR, AR, and LAR groups. The back pain might have been due to the disrupted continuity of muscles which affects all patients operated on due to colorectal cancer. The continuity of muscles is disrupted permanently in ostomy patients. This may result in the loss of motor efficiency and impairment of the motor apparatus. Metabolic stress triggered by the surgical procedure itself and the preparation thereto may lead to body weight loss, progressive fatigue, and respiratory impairment [15,16]. Muscle weakness, muscle tissue loss, and weight loss are among other factors contributing to the prevalence of back pain [17,18]. Prado et al. demonstrated that the loss of muscle mass may be related to poor outcomes [19].
Another factor responsible for pain in patients having undergone surgical procedures consists of changes in intraabdominal pressure. Intraabdominal pressure, if maintained at appropriate levels during rest and physical activity by an appropriate tone of the abdominal muscles and the pelvic and respiratory diaphragm, warrants appropriate stability of the spine. Disruption of the abdominal walls leads to changes in intraabdominal pressure, potentially translating to the development of low back pain [20,21]. In ostomy patients, the abdominal cavity is permanently open.
Scars are also formed at surgery sites, their nature depending on the surgical procedure as well as on the type of the healing process [22,23]. The type of procedure may also influence the size and the number of scars. Patients undergoing abdominoperineal resection of the rectum have incisions made within the medial line and the perineal region; an ostomy is also formed as part of the procedure [9]. This might explain the most severe intensity of lower back pain in this study group. The structure of the scar tissue and the extent of the scar may give rise to local pain as well as pain being transferred to different areas of the body [24]. This may be due to structural distortions and mobility restrictions within the scars and the surrounding tissues. The lack of tissue and fascial mobility combined with the disturbed mobility of the nervous system cells penetrating through all body layers may lead to the disruption of global postural patterns. Numerous studies suggest that manual treatment of scars by means of physiotherapy or invasive techniques such as surgical procedures may help patients regain normal pain-free functioning [25][26][27]. However, patients operated on due to colorectal cancer are not routinely referred to physiotherapeutic management of surgical incision scars. No scar physiotherapy had been offered to patients in our study. Back pain can also be explained by the patients' activity, body weight, and muscle mass being reduced after surgery. These problems are more common in patients operated on using classic methods.
As shown by our study, surgical treatment is responsible for the development of back pain regardless of the surgical approach (AR vs. LAR). However, the results observed in the LAR group were better than in the remaining groups. The benefits of laparoscopic surgery had been presented in earlier studies by other authors [1][2][3]25]. The better results observed in the laparoscopic anterior resection of the rectum group can be explained by the lower rate of post-operative pulmonary and circulatory complications leading to more timely activation of patients [28,29]. Another factor influencing the prevalence of pain in patients operated on due to colorectal cancer consists in the lack of daily physical activity which is similar to that observed in the geriatric population. The average age of the study patients was slightly higher than 63 years and was typical for colorectal cancer patients [30]. The importance of reduced activity, especially within elderly patients, was also highlighted by Ekblom-Bak et al., whose study of compliance with physical activity recommendations within an elderly population showed that minimum physical activity requirements were met by as few as 7% of subjects [31].
In addition to postural muscle weakness, chronic postoperative pain associated with perioperative nerve transection can be also a cause of spinal pain. Chronic postoperative pain is a significant clinical problem. According to Lois et al., a factor leading to postoperative spinal pain in patients treated for colorectal cancer is the presence of pain in the preoperative period [32]. Similar findings were observed by Gerbershagen et al. The study involved patients after prostatectomy surgery [33]. Other authors also cite younger age, female gender, and psychological and genetic factors as reasons for chronic postoperative pain [34,35].
Observations were carried out over a period of one year after surgery and should be treated as early results of the surgical treatment. Notably, the recurrence of colorectal cancer is most frequently observed within the first 2-3 years after surgical treatment, with early recurrences being uncommon [36]. On the other hand, pain, including low back pain, may be associated with local recurrence or spread of the disease [37].
In our study, due to the coronavirus pandemic, contact with patients in the second and third phases of the study was made using the CATI method. To ensure that there was no bias during the study, the callers of the patients had no data on the procedures provided to them. The CATI method was considered by the authors to be a safe method to survey patients during a pandemic. Other studies have previously highlighted the usefulness of this method [38].

Study Limitations
The study was burdened by certain limitations, the greatest consisting of the small number of the study group. Another limitation is the loss of contact with many patients between the first and second stages of the study. However, it should be noted that the study group consisted of consecutive patients operated on in a single high-volume center, and thus errors due to improper, non-standardized surgical procedures could be avoided. Certainly, a multi-center study could verify the collected data.
Another limitation consists of the fact that no patients operated on by means of laparoscopic abdominoperineal resection of the rectum were included in the study group. This was due to the fact that the annual number of procedures of this type within the period of the study was lower than 15. Additionally, the number of study patients operated on by means of Hartmann's procedure was small.

Conclusions
This study showed that lower back pain is a problem in patients having undergone surgeries due to colorectal cancer. The most affected group of patients consisted of those who had undergone abdominoperineal resection of the rectum. Laparoscopic surgery led to the pain symptoms being reduced as compared with other patient groups one year after surgery. Data Availability Statement: The datasets generated during and/or analyzed Turing the current study are available from the corresponding author on responsiblereques.