**2.3 Risk of cancer**

Obesity increases the risk of certain cancers such as colon, breast, endometrial, pancreatic, prostate and renal cancers [40, 41]. The outcomes of some malignancies are worse in obese individuals [42].

A database study [43] reported a lower incidence of hormone-related cancers in those who had bariatric surgery (OR 0·23, 95% CI: 0·18–0·30). Roux-en-Y gastric bypass surgery resulted in a higher reduction in hormone-related cancers than SG & AGB. However, the risk of colorectal cancer was higher (OR 2·63, 95% CI: 1·17–5·95) in the RYGB group. Other studies did not report this finding consistently [44]. Another database study showed a 34% higher risk of rectal cancer in obese individuals compared to the general population. The risk of colorectal cancer in obese individuals after bariatric surgery was like the general population [45].

Bariatric surgery has favorable effects on the incidence of all skin cancers (adjusted sub-hazard ratio 0.59, 95% CI: 0.35–0.99) [46].

#### **2.4 Long-term survival**

Studies have shown improved all-cause mortality in obese individuals who underwent bariatric surgery; however, it remains higher than in the general population.

A prospective study looked at life expectancy in over 5000 patients from the SOS study cohort [47]. After a median follow-up of 20 years, the hazards for deaths due to cardiovascular disease was 0.70 (95% CI: 0.57–0.85), death from cancer was 0.77 (95% CI: 0.61–0.96) and all-cause mortality was 0.77 (95% CI: 0.68–0.87). The median life expectancy was 3.0 years (95% CI: 1.8–4.2) longer in the bariatric surgery group than in controls but 5.5 years shorter than the general population.

Another large observational cohort study reported lower all-cause mortality rate in bariatric surgery group than control group 0.68 (95% CI: 0.57–0.81) [48] at 4.9 yr. Cardiovascular 0.53 (95% CI: 0.34–0.84) and cancer morality 0.54 (95% CI: 0.36–0.80) were also lower in bariatric surgery group.

Another case-control study reported 40% lower adjusted all-cause mortality in a case-control study (37.6 versus 57.1 deaths per 10,000 person-years p < 0.001) at 7 years [49]. However, interestingly the rate of deaths due to suicide and accidents were higher in the RYGB group compared to the control group (11.1 versus 6.4 per 10,000 person-years, p = 0.04).

#### **2.5 Functional outcomes.**

#### *2.5.1 Obstructive sleep apnea (OSA)*

Weight loss improves OSA. An RCT explored the role of RYGB and usual medical care on OSA in grade 1 & 2 obesity [50]. At 3-year follow-up, the apnea-hypoxia index (AHI) was reduced to −13.2 in the RYGB group and increased by +5 events/h in the usual care group. The risk of persistent moderate and severe OSA was also lower in the RYGB group.

A meta-analysis reported comparable improvement or remission rate in OSA with RYGB, AGB & SG (79 vs. 77 vs. 86% for, respectively) [51].

Contrary to the above findings, a meta-analysis demonstrated persistent OSA in patients after bariatric surgery despite improvement in AHI score [52]. It is possibly due to a lack of uniformity in respiratory events scoring in the studies. Detailed assessment for OSA is recommended before discontinuing continuous positive pressure airway therapy.

#### *2.5.2 Gastroesophageal reflux disease (GERD)*

Gastroesophageal reflux disease is prevalent in the obese population [53]. The influence of bariatric surgery on GERD is variable and depends on the technique.

Gastroesophageal reflux disease improved or remitted in 70% of cases at 1-year follow-up after RYGB [21]. Another prospective study investigated the role of RYGB on pre-existing GERD [54]. At 6 months follow-up, the risk of GERD was lower than before surgery (33 versus 64%). The use of anti-reflux medications and total acid exposure also decreased. De novo reflux symptoms occurred in 10% of the cases.

The effect of SG on GERD is not clear. A retrospective study [55] of the Bariatric longitudinal database (BOLD) showed that GERD symptoms persisted in 84% of the individuals after SG. De novo GERD symptoms manifested in 8.6% of cases. Fifty

*Outcomes of Bariatric Surgery DOI: http://dx.doi.org/10.5772/intechopen.105734*

per cent of patients with pre-existing GERD reported remission or improvement of GERD in another database study [21]. A systematic review [56] reported a lack of consensus in the studies. Gastroesophageal reflux disease and Barrett's esophagus are not absolute contraindications for SG; however, there is no consensus about performing SG in patients with pre-existing GERD [57].

There are conflicting data about the influence of AGB on GERD [21]. A systematic review [58] reported a decline in the prevalence of postoperative GERD compared to preoperative GERD (7.7 vs. 32.9%) after AGB. The need for anti-reflux medications (9.5 versus 27.5%), pathologic reflux (29.4 versus 55.8%), and lower esophageal pressure (16.9 versus 12.9 mmHg), all decreased in patients who underwent AGB. Fifteen percent of the individuals reported de-novo reflux symptoms.

In short, RYGB is a better option in individuals with uncontrolled severe GERD or Barrett's esophagus.

### *2.5.3 Joint pain and physical activity*

Bariatric surgery could ease joint pain and improve physical activity by reducing weight and inflammation. An observational cohort study reported significant improvement in body pains [57.6% (95% CI, 55.3%–59.9%)], physical function [76.5% (95% CI, 74.6%–78.5%)] & walk time [59.5% (95% CI, 56.4%–62.7%)] at 1 year[59]. However, most of the above symptoms relapsed between 1 and 3 years.

A systematic review showed knee pain improvement in 73% of patients after bariatric surgery [60]. An increase in the intervertebral disc height after successful bariatric surgery was reported in a prospective study [61].

A small prospective study demonstrated a reduction in pro-inflammatory markers (Interleukin 6, C-reactive protein and fibrinogen) after bariatric surgery [62]. This effect could be partly responsible for the improvement in arthritis pain.

#### **2.6 Polycystic ovary syndrome (PCOS)**

Obesity is associated with PCOS. Observational studies have reported improved PCOS symptoms (hirsutism, menstrual irregularities and hyperandrogenemia) after bariatric surgery [63, 64].

### **2.7 Renal disorders**

Obesity-related renal impairment could be due to hyperfiltration or other comorbidities such as T2DM, HTN, etc. Another prospective study showed improvement in eGFR 12 months after bariatric surgery [65].

A randomized trial of 100 patients with diabetic nephropathy reported remission of nephropathy in 82 with RYGB vs. 48% with medical therapy at 2 years [66].

Obesity-related urinary incontinence improved after bariatric surgery in the longitudinal assessment of bariatric surgery study [67]. Improvement was maintained at 3 years follow up (24.8%, 95% CI, 21.8%–26.5% among females and 12.2%, 95% CI, 9.0%–16.4% among male).

#### **2.8 Non-alcoholic fatty liver disease (NAFLD)**

The prevalence of NAFLD is high in obesity. Non-alcoholic fatty liver disease is treated by lifestyle changes and weight loss [68]. However, bariatric surgery could be considered in cases that failed to improve with medical therapy. A retrospective study of biopsy-proven fibrotic non-alcoholic steatohepatitis reported a lower cumulative incidence of major adverse liver outcomes at 10 years was 2.3% (95% CI, 0%–4.6%) in the surgery group vs. 9.6% (95% CI, 6.1%–12.9%) in the control group [69]. Another database study [70] reported a lower risk of developing cirrhosis in non-alcoholic fatty liver disease patients who underwent bariatric surgery (HR 0.31, 95% CI: 0.19–0.52).
