chemoradiotherapy ( crt ) is the preferred primary treatment modality for esophageal squamous cell carcinoma ( escc ) . however , about 13% of patients treated for escc with crt have residual tumor or experience recurrence after treatment . surgery is suggested as a salvage therapy for such patients ; however , the high mortality and morbidity rates associated with this approach are a cause for concern . recently , several authors have reported favorable outcomes with esophageal endoscopic submucosal dissection ( esd ) for recurrent escc after crt . although escc is responsive to crt , crt monotherapy can sometimes result in local recurrence . in the present study , we used esd for recurrent and residual escc lesions after crt for advanced esophageal cancer . a 64-year - old man visited our department with a complaint of dysphagia and chest discomfort that had been present for 1 month . esophagogastroduodenoscopy ( egd ) revealed an esophageal ulcerofungating mass 24 cm from the incisors ( fig . the biopsy report revealed moderately differentiated invasive squamous cell carcinoma ( scc ) . computed tomography ( ct ) and positron emission tomography ( pet ) showed subcarinal lymph node metastasis ; however , there was no other lymph node involvement or distant metastasis ( fig . the chemotherapy regimen included 12 courses of 750 mg / m / day 5-fluorouracil ( 5-fu ) plus 20 mg / m / day cisplatin for 5 days . radiotherapy including 63-gy doses in 35 fractions was concurrently delivered during the first and second chemotherapy cycles . we assessed him with egd every 6 months , and each examination until the 16-month follow - up revealed only scar tissue at the mid - esophagus . the pathological examination of the esophageal scar tissue revealed only glycogenic acanthosis . however , the follow - up egd at 22 months revealed metachronous recurrence , including an 11-mm superficial esophageal lugol - voiding lesion 33 cm from the incisors , which was involved in the previous radiation field ( fig . we then performed endoscopic ultrasonography , which showed that the lesion was confined to the mucosal layer with an intact submucosal layer . a submucosal cushion was established through the submucosal injection of a solution consisting of a mixture of sodium hyaluronate ( lg life science co. , seoul , korea ) , 10% glycerol , and 5% fructose in normal saline solution ( cerol ; jw pharmaceutical co. , seoul , korea ) ; a small amount of epinephrine ; and indigo carmine . mucosal cutting and submucosal dissection were performed with a dual knife ( kd-650q ; olympus , tokyo , japan ) . the fibrosis in the submucosal layer was very subtle ; submucosal dissection was performed without complications ; and en bloc resection was achieved within 25 minutes ( fig . 2 ) . the final pathology results showed well - differentiated scc with negative basal and lateral resection margins , and invasion to the depth of the lamina propria ( fig . 2c ) . we assessed him at regular follow - ups with egd , chest ct , and pet after esd . each egd result showed only scar tissue that was histologically negative for cancer cells . until 24 months after esd , follow - up ct and pet scans showed no evidence of local recurrence or distant metastasis . a 59-year - old man visited our department with a complaint of dyspepsia and chest discomfort that had been present for 3 months . we performed egd and found a large esophageal ulcerofungating mass 29 to 43 cm from the incisors ( fig . ct and pet showed metastasis to the left supraclavicular lymph node and multiple lymph nodes at the mediastinum ( fig . the chemotherapy regimen included 12 courses of 750 mg / m / day 5-fu plus 20 mg / m / day cisplatin for 5 days . radiotherapy at 54 gy was delivered in 30 fractions concurrently during the first and second chemotherapy cycles ( fig . 3c ) . he responded favorably , and most of the mass disappeared after crt . egd at 4 months after crt showed fibrotic scars 29 to 43 cm from the incisors . however , there were still two small residual superficial esophageal lugol - voiding lesions 38 and 43 cm from the incisors , respectively , and biopsy results revealed moderate- to high - grade squamous dysplasia . egd at 5 months after crt still showed mostly fibrotic scars at the previous lesion location ; however , two ( 2317 and 1812 mm ) superficial lugol - voiding lesions remained 38 and 43 cm from the incisors , respectively , which were located within the initial advanced escc margins ( 14 cm long ) . a submucosal cushion was established through the submucosal injection of a solution composed of a mixture of sodium hyaluronate ( lg life science ) , 10% glycerol , and 5% fructose in normal saline solution ( cerol ) ; a small amount of epinephrine ; and indigo carmine . although esd for these lesions showed mild submucosal fibrosis caused by the earlier crt , we achieved en bloc resection for both lesions without any complications within 55 minutes ( fig . 4 ) . the final pathology results revealed well - differentiated scc confined within the lamina propria 38 cm from the incisors , and high - grade squamous dysplasia 43 cm from the incisors . each egd result showed only scar tissue that was histologically negative for cancer cells . until 32 months after esd , follow - up a 64-year - old man visited our department with a complaint of dysphagia and chest discomfort that had been present for 1 month . esophagogastroduodenoscopy ( egd ) revealed an esophageal ulcerofungating mass 24 cm from the incisors ( fig . the biopsy report revealed moderately differentiated invasive squamous cell carcinoma ( scc ) . computed tomography ( ct ) and positron emission tomography ( pet ) showed subcarinal lymph node metastasis ; however , there was no other lymph node involvement or distant metastasis ( fig . the chemotherapy regimen included 12 courses of 750 mg / m / day 5-fluorouracil ( 5-fu ) plus 20 mg / m / day cisplatin for 5 days . radiotherapy including 63-gy doses in 35 fractions was concurrently delivered during the first and second chemotherapy cycles . we assessed him with egd every 6 months , and each examination until the 16-month follow - up revealed only scar tissue at the mid - esophagus . the pathological examination of the esophageal scar tissue revealed only glycogenic acanthosis . however , the follow - up egd at 22 months revealed metachronous recurrence , including an 11-mm superficial esophageal lugol - voiding lesion 33 cm from the incisors , which was involved in the previous radiation field ( fig . we then performed endoscopic ultrasonography , which showed that the lesion was confined to the mucosal layer with an intact submucosal layer . a submucosal cushion was established through the submucosal injection of a solution consisting of a mixture of sodium hyaluronate ( lg life science co. , seoul , korea ) , 10% glycerol , and 5% fructose in normal saline solution ( cerol ; jw pharmaceutical co. , seoul , korea ) ; a small amount of epinephrine ; and indigo carmine . mucosal cutting and submucosal dissection were performed with a dual knife ( kd-650q ; olympus , tokyo , japan ) . the fibrosis in the submucosal layer was very subtle ; submucosal dissection was performed without complications ; and en bloc resection was achieved within 25 minutes ( fig . 2 ) . the final pathology results showed well - differentiated scc with negative basal and lateral resection margins , and invasion to the depth of the lamina propria ( fig . 2c ) . we assessed him at regular follow - ups with egd , chest ct , and pet after esd . each egd result showed only scar tissue that was histologically negative for cancer cells . until 24 months after esd , follow - up ct and pet scans showed no evidence of local recurrence or distant metastasis . a 59-year - old man visited our department with a complaint of dyspepsia and chest discomfort that had been present for 3 months . we performed egd and found a large esophageal ulcerofungating mass 29 to 43 cm from the incisors ( fig . ct and pet showed metastasis to the left supraclavicular lymph node and multiple lymph nodes at the mediastinum ( fig . the chemotherapy regimen included 12 courses of 750 mg / m / day 5-fu plus 20 mg / m / day cisplatin for 5 days . radiotherapy at 54 gy was delivered in 30 fractions concurrently during the first and second chemotherapy cycles ( fig . egd at 4 months after crt showed fibrotic scars 29 to 43 cm from the incisors . however , there were still two small residual superficial esophageal lugol - voiding lesions 38 and 43 cm from the incisors , respectively , and biopsy results revealed moderate- to high - grade squamous dysplasia . egd at 5 months after crt still showed mostly fibrotic scars at the previous lesion location ; however , two ( 2317 and 1812 mm ) superficial lugol - voiding lesions remained 38 and 43 cm from the incisors , respectively , which were located within the initial advanced escc margins ( 14 cm long ) . a submucosal cushion was established through the submucosal injection of a solution composed of a mixture of sodium hyaluronate ( lg life science ) , 10% glycerol , and 5% fructose in normal saline solution ( cerol ) ; a small amount of epinephrine ; and indigo carmine . mucosal cutting and submucosal dissection were performed with a dual knife ( kd-650q ) . although esd for these lesions showed mild submucosal fibrosis caused by the earlier crt , we achieved en bloc resection for both lesions without any complications within 55 minutes ( fig . 4 ) . the final pathology results revealed well - differentiated scc confined within the lamina propria 38 cm from the incisors , and high - grade squamous dysplasia 43 cm from the incisors . each egd result showed only scar tissue that was histologically negative for cancer cells . until 32 months after esd , follow - up ct and pet showed no evidence of local recurrence or distant metastasis . the optimal treatment for these lesions is controversial ; however , recent studies have shown that esd could be an option [ 2 - 4 ] . saito et al .   reported that esd can be used for the en bloc resection of recurrent or residual superficial esophageal tumors after crt , with a high rate of cr and without greater risk than for endoscopic mucosal resection . they used esd to treat four patients with local recurrence of escc , and successfully achieved en bloc resection in all patients . furthermore , takeuchi et al .   reported that esd represents an acceptable treatment option for recurrent or residual escc involving only the submucosal layer without metastasis after crt because of its effect in improving local control . they successfully treated 19 lesions in 19 patients who underwent salvage esd . at a median follow - up of 54.6 months , no local recurrence was noted at the treatment site in any patient . the 3-year overall survival rate after salvage esd was 74% . koizumi et al .   also reported 12 cases of salvage esd for esophageal scc after a definitive crt . the median survival duration after salvage esd for all patients was 18 months ( range , 8 to 70 ) , and 9 of 12 patients have survived . table 1 shows a summary of the findings of the three previous reports along with the findings in our cases . a high level of technical skill is necessary to achieve en bloc resection and to avoid complications such as perforation . moreover , when there is fibrosis in the submucosal layer , esophageal esd becomes more technically demanding . because crt induces some fibrosis in the esophageal wall , fibrosis at the treatment location can be predicted . there are concerns about the technical difficulty of esd and possible complications from esd after crt . although data on the outcomes of esophageal esd after crt are limited , several japanese authors have reported favorable outcomes for esophageal esd after crt [ 3,8 - 10 ] . safe management of mild fibrosis caused by crt and acceptable outcomes can be achieved depending on technical skill of the esd endoscopists . in this report , we presented two cases of recurrent and residual escc treated successfully with esd after crt . no complications such as perforation or major bleeding were observed . with a longer follow - up duration , tumors may recur at the original site ; however , there has been no recurrence for 26 months in case 1 and for 32 months in case 2 . although it requires patients to be assessed for a long period , salvage esd can be considered an effective and safe treatment option that requires a certain level of technical expertise when locoregional failure is limited to the mucosal layer with no distant metastases .
we report two cases of endoscopic submucosal dissection ( esd ) for recurrent or residual esophageal squamous cell carcinoma ( escc ) lesions after chemoradiotherapy for advanced esophageal cancer . 
 case 1 involved a 64-year - old man who had previously undergone chemoradiotherapy for advanced escc and achieved a complete response ( cr ) for 22 months , until metachronous recurrent superficial escc was detected on follow - up esophagogastroduodenoscopy ( egd ) . 
 we performed esd and found no evidence of recurrence for 24 months . 
 case 2 involved a 59-year - old man who had previously undergone chemoradiotherapy for advanced escc . 
 he responded favorably to treatment , and most of the tumor had disappeared on follow - up egd 4 months later . 
 however , there were two residual superficial esophageal lugol - voiding lesions . 
 we performed esd , and he had a cr for 32 months thereafter . 
 esd can be considered a viable treatment option for recurrent or residual superficial escc after chemoradiotherapy for advanced esophageal cancer .