Inflammatory Myofibroblastic Tumor of the Sigmoid Colon in an Infant: A Case Report and Literature Review.

Inflammatory myofibroblastic tumor (IMT) infrequently involves the sigmoid colon, and has not previously been described in an infant sigmoid colon.An inflammatory myofibroblastic tumor arose from the sigmoid colon of an 11-month-old boy, confirmed by anaplastic lymphoma kinase (ALK), smooth muscle actin (SMA) and desmin immunohistochemical staining. The patient recovered well after complete resection of the tumor.Sigmoid IMT can occur in infancy. This eighth case is the youngest so far. The child did well after surgical resection.

[A Case in Which a Laparotomy Transition, in a Patient with Sigmoid Colon Cancer, Prevented Peritoneal Metastasis from Being Missed].

We report a case of laparoscopic sigmoidectomy for sigmoid colon cancer where a laparotomy transition prevented peritoneal metastasis from being missed. Case: A 64-year-old woman was diagnosed with sigmoid colon cancer. Computed tomography revealed a large bowel obstruction and a 12 mm wide basal bulge in the gallbladder. A laparoscopic sigmoidectomy( D3 dissection)was first performed, and intra-abdominal observation revealed no disseminated nodules. A laparoscopic cholecystectomy was performed continuously but, due to strong adhesions, a laparotomy was administered. Three disseminated nodules were observed in the omentum during the laparotomy and a postoperative pathological examination revealed pT4aN1b(2/23)M1c1(P2), pStage Ⅳc. Adjuvant chemotherapy of 8 courses of CAPOX was performed and there has been no recurrence 20 months after surgery.

Case report of polymyalgia rheumatica in a male patient with three different neoplasms treated with pembrolizumab.

In this manuscript we aim to describe a particular case of a 63 years-old man who developed three different malignancies (one was a rare case of breast cancer) among nearly five years. In particular, for the diagnosis of melanoma, he was treated with pembrolizumab, a PD-1 inhibitor. After few months of treatment with pembrolizumab, the patient reported the onset of musculoskeletal symptoms such as inflammatory pain at the shoulders and morning stiffness, with raised CRP and ESR and imaging evidence of bursitis and tenosynovitis. A polymyalgia-like syndrome was diagnosed. Understanding if these manifestations are linked to the use of pembrolizumab or to a paraneoplastic syndrome, and how to manage the patient, was the real challenge.

[Cystic lymphangioma of the rectum-sigmoid in a public hospital in Lima-Peru: case report]. / Linfangioma quístico de recto-sigmoides en un hospital público de Lima, Perú: reporte de caso.

Lymphangiomas are benign lesions due to a developmental malformation in the lymphatic system that occurs during the embryonic stage. They are more frequent in children. They can be found in the abdominal cavity, being the involvement of the gastrointestinal tract occasionally. The clinical presentation is varied, depending on the location of the lymphangiomas, and may have asymptomatic forms and, occasionally, present with abdominal pain, changes in defecation, rectal bleeding, etc. The diagnosis is made by endoscopy, auxiliary images and is confirmed by histology. We present a case of cystic rectal-sigmoid lymphangioma that we had in our hospital; the patient presented with proctalgia, alternating evacuation and intermittent rectal bleeding. Physical examination was without significant alterations. During the colonoscopy, at the level of the rectum and sigmoids, multiple protruded lesions were found, whose surface was smooth, translucent and bluish in color, with some pseudodiverticular holes, predominantly of the rectum. Endoscopic ultrasound revealed thickening of the submucosa at the level of the rectum with multiple anechoic, microcystic images, some of them with fine septa. The definitive diagnosis was made by histopathology, which describes dilated lymphatic ducts, surrounded by endothelial cells, findings consistent with cystic rectal-sigmoid lymphangioma.

Mortality From Postscreening (Interval) Colorectal Cancers Is Comparable to That From Cancer in Unscreened Patients-A Randomized Sigmoidoscopy Trial.

BACKGROUND & AIMS: Endoscopic screening for colorectal cancer (CRC) is performed at longer time intervals than the fecal occult blood test or screenings for breast or prostate cancer. This causes concerns about interval cancers, which have been proposed to progress more rapidly. We compared outcomes of patients with interval CRCs after sigmoidoscopy screening vs outcomes of patients with CRC who had not been screened. METHODS: We performed a secondary analysis of a randomized sigmoidoscopy screening trial in Norway with 98,684 participants (age range, 50-64 years) who were randomly assigned to groups that were (n = 20,552) or were not (n = 78,126) invited for sigmoidoscopy screening from 1999 through 2001; participants were followed up for a median 14.8 years. We compared CRC mortality and all-cause mortality between individuals who underwent screening and were diagnosed with CRC 30 days or longer after screening (interval cancer group, n = 163) and individuals diagnosed with CRC in the nonscreened group (controls, n = 1740). All CRCs in the control group were identified when they developed symptoms (clinically detected CRCs). Analyses were stratified by cancer site. We used Cox regression to estimate hazard ratio (HRs), adjusted for age and sex. RESULTS: Over the follow-up period, 43 individuals in the interval cancer group died from CRC; among controls, 525 died from CRC. CRC mortality (adjusted HR, 0.98; 95% confidence interval, 0.72-1.35; P = .92), rectosigmoid cancer mortality (adjusted HR, 1.10; 95% confidence interval, 0.63-1.92; P = .74), and all-cause mortality (adjusted HR, 0.99; 95% confidence interval, 0.76-1.27; P = .91) did not differ significantly between the interval cancer group and controls. CONCLUSIONS: In this randomized sigmoidoscopy screening trial, mortality did not differ significantly between individuals with interval CRCs and unscreened patients with clinically detected CRCs. ClinicalTrials.gov identifier: NCT00119912.

Effects of Training and Feedback on Accuracy of Predicting Rectosigmoid Neoplastic Lesions and Selection of Surveillance Intervals by Endoscopists Performing Optical Diagnosis of Diminutive Polyps.

BACKGROUND & AIMS: Real-time differentiation of diminutive polyps (1-5 mm) during endoscopy could replace histopathology analysis. According to guidelines, implementation of optical diagnosis into routine practice would require it to identify rectosigmoid neoplastic lesions with a negative predictive value (NPV) of more than 90%, using histologic findings as a reference, and agreement with histology-based surveillance intervals for more than 90% of cases. METHODS: We performed a prospective study with 39 endoscopists accredited to perform colonoscopies on participants with positive results from fecal immunochemical tests in the Bowel Cancer Screening Program at 13 centers in the Netherlands. Endoscopists were trained in optical diagnosis using a validated module (Workgroup serrAted polypS and Polyposis). After meeting predefined performance thresholds in the training program, the endoscopists started a 1-year program (continuation phase) in which they performed narrow band imaging analyses during colonoscopies of participants in the screening program and predicted histological findings with confidence levels. The endoscopists were randomly assigned to groups that received feedback or no feedback on the accuracy of their predictions. Primary outcome measures were endoscopists' abilities to identify rectosigmoid neoplastic lesions (using histology as a reference) with NPVs of 90% or more, and selecting surveillance intervals that agreed with those determined by histology for at least 90% of cases. RESULTS: Of 39 endoscopists initially trained, 27 (69%) completed the training program. During the continuation phase, these 27 endoscopists performed 3144 colonoscopies in which 4504 diminutive polyps were removed. The endoscopists identified neoplastic lesions with a pooled NPV of 90.8% (95% confidence interval 88.6-92.6); their proposed surveillance intervals agreed with those determined by histologic analysis for 95.4% of cases (95% confidence interval 94.0-96.6). Findings did not differ between the group that did vs did not receive feedback. Sixteen endoscopists (59%) identified rectosigmoid neoplastic lesions with NPVs greater than 90% and selected surveillance intervals in agreement with those determined from histology for more than 90% of patients. CONCLUSIONS: In a prospective study following a validated training module, we found that a selected group of endoscopists identified rectosigmoid neoplastic lesions with pooled NPVs greater than 90% and accurately selected surveillance intervals for more than 90% of patients over the course of 1 year. Providing regular interim feedback on the accuracy of neoplastic lesion prediction and surveillance interval selection did not lead to differences in those endpoints. Monitoring is suggested, as individual performance varied. ClinicalTrials.gov no: NCT02516748; Netherland Trial Register: NTR4635.

Clinical and Molecular Features of Post-Colonoscopy Colorectal Cancers.

BACKGROUND & AIMS: Post-colonoscopy colorectal cancers (PCCRCs) may arise from missed lesions or due to molecular features of tumors that allow them to grow rapidly. We aimed to compare clinical, pathology, and molecular features of PCCRCs (those detected within 6-60 months of colonoscopy) and detected CRCs (those detected within 6 months of a colonoscopy). METHODS: Within a population-based cross-sectional study of incident CRC cases in Utah (from 1995 through 2009), we identified PCCRCs (those cancers that developed within 5 years of a colonoscopy) and matched the patients by age, sex, and hospital site to patients with detected CRC. Archived specimens were retrieved and tested for microsatellite instability (MSI), CpG island methylation, and mutations in KRAS and BRAF. There were 2659 cases of CRC diagnosed within the study window; 6% of these (n = 159) were defined as PCCRCs; 84 of these cases had tissue available and were matched to 84 subjects with detected CRC. RESULTS: Higher proportions of PCCRCs than detected CRCs formed in the proximal colon (64% vs 44%; P = .016) and were of an early stage (86% vs 69%; P = .040). MSI was observed in 32% of PCCRCs compared with 13% of detected CRCs (P = .005). The other molecular features were found in similar proportions of PCCRCs and detected CRCs. In a multivariable logistic regression, MSI (odds ratio, 4.20; 95% CI, 1.58-11.14) was associated with PCCRC. There was no difference in 5-year survival between patients with PCCRCs vs detected CRCs. CONCLUSION: In this population-based cross-sectional study of incident CRC cases in Utah, we found PCCRCs to be more likely to arise in the proximal colon and demonstrate MSI, so PCCRCs and detected CRC appear to have different features or processes of tumorigenesis. Additional studies are needed to determine if post-colonoscopy cancers arise through a specific genetic pathway.

Surveillance Colonoscopy for Ulcerative Colitis-Associated Colorectal Cancer Offers Better Overall Survival in Real-World Surgically Resected Cases.

OBJECTIVES: To determine the effectiveness of surveillance colonoscopy (SC) and optimize its use by assessing real-world surgically resected cases of ulcerative colitis (UC)-associated colorectal cancer (CRC) and dysplasia. METHODS: Clinicopathological data of 406 (238 CRC and 168 dysplasia) patients who underwent surgical resection in 10 UC specialized institutions were retrospectively reviewed. The overall survival (OS) rates were compared between the SC and non-SC groups. The incidence of and risk factors for early-onset CRC (<8 years after UC onset) were identified. The distribution of CRC lesions was also assessed. RESULTS: Cancer stages were significantly more advanced in the non-SC group than in the SC group (P < 0.001). The patients in the SC group showed significantly better OS than those in the non-SC group (5-year OS: 89% vs 70%; log-rank test: P = 0.001). Seventeen percent of patients developed CRC within 8 years after UC onset. The age at UC onset was a risk factor and a good predictor of early-onset CRC (<8 years) (P < 0.01; AUC: 0.85). The most common sites of CRC were the rectum (51%) and sigmoid colon (20%). Multiple CRC was identified in 16% of patients. CONCLUSIONS: Surveillance colonoscopy was effective and improved the OS in patients with UC. We recommend that patients with late-onset UC (>40 years) undergo SCs earlier because of the high incidence of CRC within 8 years of UC onset. Moreover, the rectum and sigmoid colon should be more thoroughly examined.

Metachronous metastasis to inguinal lymph nodes from sigmoid colon adenocarcinoma with abdominal wall metastasis: a case report.

BACKGROUND: Inguinal lymph node metastasis from rectum is uncommon but well-known occurrence, whereas that from colon adenocarcinoma is extremely rare. Inguinal lymph node metastasis from colon adenocarcinoma has only been reported in previous cases involving primary tumor invasion of the abdominal wall, or in those involving colon cancer metastasis to external iliac lymph nodes. We describe a case of inguinal lymph node metastasis from colon cancer without primary tumor invasion to the abdominal wall. CASE PRESENTATION: A 42-year-old female, who had undergone twice cesarean sections before, underwent open sigmoidectomy for sigmoid colon adenocarcinoma and received 12 cycles of FOLFOX regimen as adjuvant chemotherapy. Two years after sigmoidectomy, a follow-up CT scan revealed enlarged inguinal lymph nodes as well as growth of enhanced mass lesions on the abdominal wall at site of the cesarean section scar. Biopsy of both lesions revealed well-differentiated adenocarcinoma, and immunohistochemistry demonstrated positive expression of CDX2, substantiating its gastrointestinal origin. We therefore performed dissection of left inguinal lymph nodes and mass lesion of the abdominal wall. The patient died 51 months after lymph node dissection. CONCLUSIONS: This is the first reported case of inguinal lymph node metastasis from colon cancer without invasion of the primary tumor to the abdominal wall or without involvement of the external iliac lymph nodes, suggesting that the pathway of inguinal metastasis originated from the abdominal wall metastasis. When inguinal lymph node metastasis from colon cancer is suspected, if an R0 resection was possible, inguinal lymph node dissection may be a potentially effective treatment.

Multiple metastases of bones and sigmoid colon after mastectomy for ductal carcinoma in situ of the breast: a case report.

BACKGROUND: The prognosis of ductal carcinoma in situ (DCIS) is reportedly well. Extremely rare patients with DCIS develop distant breast cancer metastasis without locoregional or contralateral recurrence. This is the first report of multiple bones and sigmoid colon metastases from DCIS after mastectomy. CASE PRESENTATION: A 43-year-old woman was diagnosed with DCIS, and she received mastectomy, followed by endocrine therapy and target therapy. During the following-up, convulsions and pain on the legs were complaint. Therefore, Computed Tomography (CT) on bones and positron emission tomography (PET) for whole body were examined in order. Multiple bones and sigmoid colon were under the suspect of metastases, which were then verified by biopsy in the left ilium and colonoscopy respectively. CONCLUSIONS: This case reveals the heterogeneous behavior and the potential poor outcome of DCIS, regular examination and surveillance are necessary even though the distant metastasis rate in DCIS is low.

Management of Malignant Large-Bowel Obstruction.

CASE SUMMARY: An otherwise healthy 59-year-old man presented to the emergency department with 2 weeks of narrowed stools, 5 days of obstipation, and 1 day of abdominal pain, nausea, and vomiting. Computed tomography revealed an obstructing sigmoid mass without evidence of metastatic disease, and the CEA was 1.2 ng/mL. Flexible sigmoidoscopy confirmed a circumferentially obstructing distal sigmoid neoplasm. Endoscopic stent placement was immediately followed by a firm distended abdomen. An upright radiograph obtained following the procedure demonstrated free intraperitoneal air. An emergent Hartmann procedure was performed for iatrogenic colon perforation in a patient with malignant obstruction and chronic dilation of the proximal colon.

[A Case of Rectal Neuroendocrine Carcinoma That Developed Two Years after Curative Resection for Sigmoid Colon Cancer].

We report a rare case ofrectal neuroendocrine carcinoma(NEC)following sigmoidectomy of sigmoid colon cancer. NEC of the rectum is a rare disease. It has an extremely poor prognosis and a high potential for malignancy with hematogenous and lymph node metastases. A 90-year-old man who had carcinoma ofthe sigmoid colon 2 years ago was found to have rectal NEC based on endoscopy findings. He underwent the Hartmann operation. Histological and immunohistochemical analyses showed NEC. Four months after the surgery, he developed local recurrence with lymph node metastasis. He was not administered chemotherapy because ofhis old age. Although the patient needed strict outpatient care, he remained symptom-free 4 months after the Hartmann operation.

Endometriosis-associated recto-sigmoid cancer: a case report.

BACKGROUND: Endometriosis is a relatively common condition in women of reproductive age. Malignant transformation of intestinal endometriosis is a very rare event. We report a case in which a patient with a history of endometriosis underwent surgery for malignant intestinal endometriosis. CASE PRESENTATION: A 55-year-old woman complained of rectorrhagia and intermittent abdominal pain. A neoplasm was revealed by colonoscopy, CT scan and F18-FDG PET/CT of the recto-sigmoidal colon. The patient underwent a rectal anterior resection, hysterectomy and bilateral salpingo-oophorectomy for treatment. According to the histological and immunohistochemical presentation, the diagnosis of endometriosis-associated recto-sigmoid cancer was confirmed. The patient was treated with adjuvant chemotherapy for 6 months. During the follow-up appointment 22 months later, there was clinical and radiographic evidence of recurrence in the rectum. The patient received chemotherapy again and will receive another surgery after two more cycles of chemotherapy. CONCLUSION: We report a case of malignant intestinal endometriosis. Although there is no standard therapy for malignant intestinal endometriosis due to the rarity of this disease, surgery and adjuvant chemotherapy seemed to be rational. This case indicates that local recurrence may be a common situation after standard therapy.

Severe abdominopelvic actinomycosis with colon perforation and hepatic involvement mimicking advanced sigmoid colon cancer with hepatic metastasis: a case study.

BACKGROUND: Actinomycosis is a rare chronic invasive disease caused by Actinomyces spp. Although abdominopelvic actinomycosis, which involves the colon and the pelvic organs extensively, has been frequently reported, abdominopelvic actinomycosis presenting with colon perforation and hepatic involvement concurrently has yet to be reported. CASE PRESENTATION: A 55-year-old woman presented at the emergency room with squeezing epigastric pain. Palpation of the abdomen revealed a hard mass with no acute peritoneal signs. Vital signs were normal range except for tachycardia. Initial laboratory testing revealed leukocytosis, anemia, elevated C-reactive protein (CRP), hypoalbuminemia; and normal AST/ALT and BUN/creatinine. CT scan of the abdomen-pelvis revealed a microperforations of the sigmoid colon, abscess in the left lower quadrant and hepatic lesion. Furthermore, there was a large infiltrating conglomerated mass invading the urinary bladder, left adnexa, sigmoid, left inguinal canal and left pelvic wall area. Ultrasound revealed an intra-uterine device (IUD). All these findings initially raised a suspicion of malignancy such as advanced cancer of the colon with liver metastasis. Despite the rarity of the disease, actinomycosis were not excluded because of the IUD found on ultrasound. Parenteral antibiotics and percutaneous drainage of abdomen abscess as well as fasting with total parental nutrition were prescribed for sigmoid perforation and abscess. After 10 days of conservative treatment, no remarkable change was detected in conglomerated mass invading pelvis. Furthermore, the finding of newly developed mechanical small bowel obstruction warranted surgery. Exploratory laparotomy was performed for the removal of perforated colon, obstructive small bowel and organs involved and postoperative histology confirmed a diagnosis of colonic actinomycosis. The patient made an uneventful recovery and was started on a 6-month course of penicillin. CONCLUSIONS: Abdominopelvic actinomycosis presenting with colon perforation and hepatic involvement is extremely rare; however, it is clinically similar to advanced colon cancer with liver metastasis, therefore, complicating the preoperative diagnosis. A diagnosis of abdominopelvic actinomycosis should be considered in patients with a history of IUD and chronic abdominal pain, along with an abdominal mass or cutaneous abscess. If surgery is indicated, preoperative empirical antibiotic therapy for actinomycosis and frozen biopsy during surgery may be considered.

[Bilateral Metastatic Lung Tumor with Different Primary Organs].

A 72-year-old woman with a history of surgery for left breast cancer was found to have sigmoid colon cancer and solitary pulmonary tumor of left upper lobe. We diagnosed adenocarcinoma of the unknown origin by a transbronchial biopsy. We performed left upper segmentectomy and sigmoidectomy. Left pulmonary tumor was diagnosed metastatic lung tumor from breast cancer. A right pulmonary tumor was confirmed by chest computed tomography(CT) after sigmoidectomy. It was also considered to be metastasis from breast cancer and treated with vinorelbine ditartrate. Since no effect was observed by chemotherapy, tumor was surgically removed by wedge resection. Right pulmonary tumor was pathologically diagnosed as metastasis from sigmoid colon cancer. In suspicious case of pulmonary metastases from double cancer, the possibility of different lesions from different primary site should be kept in mind.

[A Case of Sigmoid Colon Cancer Identified by Gastric Perforation].

We report a case of sigmoid colon cancer that was incidentally found using CT that was performed for upper abdominal pain. An 83-year-old man with a long history of lung tuberculosis and idiopathic pulmonary fibrosis presented with upper abdominal pain. CT findings revealed free gas around the stomach. He was diagnosed with upper gastrointestinal perforation and his condition improved after undergoing conservative treatment. Upper endoscopy revealed an irregular ulcer at the angular incisure of the stomach with thickened folds, but biopsy resulted in a Group 1 classification. CT findings also incidentally revealed sigmoid colonic wall thickness, and colonoscopy showed a type Ⅰ lesion in the sigmoid colon, which biopsy resulted in Group 5, and we performed sigmoidectomy for sigmoid colon cancer under a combination of spine-subarachnoid and epidural anesthesia because of his respiratory dysfunction.

[A Case of Sigmoid Colon Cancer with Locally Advanced Infiltration Curatively Resected after CapeOX Therapy].

A 68-year-old man presented with malaise and abdominal swelling.Lower gastrointestinal endoscopy revealed a type 2 circumferential sigmoid colon cancer.Computed tomography suggested the cancer infiltrating bladder and abdominal wall with abscess.Because of locally advanced infiltration, the patient was treated with capecitabine plus oxaliplatin(CapeOX) plus bevacizumab therapy after loop-colostomy.After 2 courses of chemotherapy, a CT revealed tumor reduction and increased abscess, which was punctured drainage.After 4 courses of chemotherapy, a CT revealed abscess reduction, we tried to operation.Sigmoidectomy with combined resection of abdominal wall and bladder total hysterectomy and fascia lata grafting were performed.The pathological diagnosis was tub1, T4b, ly2, v2, PN0, N0, M0, Stage II, pR0, Grade I a.We reported a case of curative resection of locally advanced sigmoid colon cancer treated with combined resection of bladder and abdominal wall after CapeOX therapy.

[Sigmoid colon cancer with intussusception prolapsing through the anus treated by elective laparoscopic radical surgery].

An 86-year-old man was brought in ambulance to our hospital because of sudden hematochezia and abdominal pain during defecation. Intestinal prolapse approximately 80mm from the anus and a type 1 tumor 50mm in size on the mucosal surface were detected. The intestinal prolapse was manually repositioned, and the reduction of the intussusception was confirmed by computed tomography (CT). Following colonoscopy and abdominal-enhanced CT, a sigmoid colon cancer without distant metastases was detected. Elective laparoscopic radical surgery was performed. The present study described a rare case of sigmoid colon cancer with an intussusception prolapsing through the anus and highlighted the treatment strategy by reviewing 48 previous cases. The treatment strategy employed was as follows:first, manual repositioning of the intestinal prolapse was attempted;and second, the presence of intussusception was confirmed by CT. In cases when repositioning of the intussusception was not possible, even with the use of an endoscope or contrast enema, emergency surgery was required.

Early detection versus primary prevention in the PLCO flexible sigmoidoscopy screening trial: Which has the greatest impact on mortality?

BACKGROUND: Screening for colorectal cancer (CRC) with flexible sigmoidoscopy (FS) has been shown to reduce CRC mortality. The current study examined whether the observed mortality reduction was due primarily to the prevention of incident CRC via removal of adenomatous polyps or to the early detection of cancer and improved survival. METHODS: The Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial randomized 154,900 men and women aged 55 to 74 years. Individuals underwent FS screening at baseline and at 3 or 5 years versus usual care. CRC-specific survival was analyzed using Kaplan-Meier curves and proportional hazards modeling. The authors estimated the percentage of CRC deaths averted by early detection versus primary prevention using a model that applied intervention arm survival rates to CRC cases in the usual-care arm and vice versa. RESULTS: A total of 1008 cases of CRC in the intervention arm and 1291 cases of CRC in the usual-care arm were observed. Through 13 years of follow-up, there was no significant difference noted between the trial arms with regard to CRC-specific survival for all CRC (68% in the intervention arm vs 65% in the usual-care arm; P =.16) or proximal CRC (68% vs 62%, respectively; P = .11) cases; however, survival in distal CRC cases was found to be higher in the intervention arm compared with the usual-care arm (77% vs 66%; P<.0001). Within each arm, symptom-detected cases had significantly worse survival compared with screen-detected cases. Overall, approximately 29% to 35% of averted CRC deaths were estimated to be due to early detection and 65% to 71% were estimated to be due to primary prevention. CONCLUSIONS: CRC-specific survival was similar across arms in the PLCO trial, suggesting a limited role for early detection in preventing CRC deaths. Modeling suggested that approximately two-thirds of avoided deaths were due to primary prevention. Future CRC screening guidelines should emphasize primary prevention via the identification and removal of precursor lesions. Cancer 2017;123:4815-22. © 2017 American Cancer Society.