there have been remarkable advances in chemotherapy for unresectable , recurrent colon cancer in recent years . the main chemotherapy regimens are folfox and folfiri , which consist of combinations of 5-fluorouracil , irinotecan , oxaliplatin and leucovorin ( lv ) , and efficacy rates of approximately 5060% have been reported [ 1 , 2 ] . more recently , molecularly targeted drugs , such as bevacizumab , cetuximab and panitumumab , have been developed and have been successful in further extending patient survival [ 3 , 4 , 5 ] . in general , when these drugs are administered on an outpatient basis , it is necessary to insert a port in order to secure a central venous route . for example , there are complications associated with creation of the port , and there are subsequent cosmetic issues and long periods of time that the patient is required to remain in hospital . there is also the inconvenience associated with wearing the drug reservoir in case of continuous drug administration , as well as adverse drug reactions ( adrs ) [ 6 , 7 ] . recent reports for unresectable and recurrent colon cancer have documented response rates of 3341.7% and efficacy in the case of administration of tegafiri , a combination of oral and intravenous anticancer drugs ( lv at 90 mg / day and tegafur - uracil ( uft ) at 250 mg / m / day in three divided doses per day for 14 days , plus 1.5-hour infusion of irinotecan at 240 mg / m2 on day 1 ) [ 8 , 9 ] . however , adrs , including grade 3/4 neutropenia , nausea , emesis and diarrhea , manifested in 1020% of patients . accordingly , we took into consideration the results reported by etienne - grimaldi et al .   and hoff et al . , and devised the modified tegafiri ( mtegafiri ) regimen ( lv at 50 mg / day and uft at 300 mg / m / day , both in two divided doses per day for 14 days , plus 1.5-hour infusion of irinotecan at 100 mg / m2 on day 1 ) with the objectives of minimizing adrs and making administration more convenient . we then employed this new regimen to treat a japanese male with synchronous multiple liver metastases of colon cancer . that patient achieved complete response ( cr ) , and the details of this case are reported below . the patient was a 58-year - old japanese male who presented with a chief complaint of lower abdominal pain . a blood work - up showed no abnormalities of leukocyte , erythrocyte or platelet counts , and the biochemical test results for total bilirubin , liver enzymes , alkaline phosphatase , and serum creatinine were all within normal ranges . analysis of tumor markers found that cea was normal at 1.7 ng / ml ( normal : 5 ng / ml ) , whereas ca19 - 9 was abnormally elevated at 137.5 u / ml ( normal : 37 u / ml ) . barium enema and colon fiberscopy confirmed the presence of a large , 4  4 cm tumor in the descending colon . a computed tomography ( ct ) scan showed multiple metastatic lesions in both lobes of the liver ( fig . since the primary tumor in the descending colon was partially obstructing the intestinal tract , it was first resected , and then left hemi - colectomy was performed . in accordance with the tnm classification , the tumor was diagnosed as t3 , n2 , m1 ( multiple , unresectable metastatic lesions were present in both lobes of the liver , stage iv ) . 5 weeks after surgery , levels of the tumor marker ca19 - 9 had become normal at 18.2 u / ml . when informed consent was obtained for treatment aimed at the unresectable liver metastatic lesions , the patient desired that any adrs be mild , that he be able to continue work as usual , that an indwelling port and hospitalization be avoided , and that the number of required visits to the hospital be minimized . the abdominal ct taken following completion of 6 courses of the mtegafiri regimen is shown in figure 1b . the largest metastatic lesion in the liver had decreased in size from 3  3 cm to 0.5  0.5 cm , and the other lesions also tended to be reduced in size . based on the recist criteria , a partial response was confirmed . the abdominal ct taken following completion of 12 courses of the mtegafiri regimen ( 9 months after starting chemotherapy ) is shown in figure 1c , and the results indicated cr . to date , the patient has completed 32 courses of the mtegafiri regimen ( cr has been maintained for 15 months ) , and cr continues . there were no adrs during the first 2 courses of chemotherapy , and therapy was continued . after starting the third course , the only other adr that manifested during the chemotherapy was grade 1 neutropenia , and there has been no occurrence of any gastrointestinal symptoms such as anorexia or nausea . the national comprehensive cancer network clinical practice guidelines in oncology   and the japanese colorectal cancer treatment guidelines   list 5-fluorouracil as the main drug for chemotherapy of advanced , recurrent colon cancer , along with irinotecan , oxaliplatin , bevacizumab , cetuximab and panitumumab [ 1 , 2 , 3 , 4 , 5 ] . however , due to an increase in the types of drugs available and the combinations in which they are used , various problems have arisen , such as the need to establish an administration route and the specific adrs associated with these drugs [ 6 , 7 ] . the most frequently used regimens are folfox and folfiri , and when these regimens are administered on an outpatient basis , it is generally necessary to insert a port in order to secure a central venous route . at the time of insertion , there can be complications , including pneumothorax , hemothorax and arterial puncture , and then there are cosmetic issues after insertion . in addition , it is generally necessary for the patient to visit the hospital every 2 weeks for treatment and the time needed for drug administration is long , as is the time the patient is detained in the hospital . the adrs reportedly occurring with the folfox regimen , particularly those associated with oxaliplatin , include symptoms of peripheral neuropathy , such as numbness of the fingertips , and manifest in approximately 1830% of all patients [ 6 , 7 ] . it has also been reported that sensory impairment can persist for long periods of time , and this can cause various impediments in the course of daily life and work . with the goal of minimizing these issues , treatment regimens for unresectable recurrent colon cancer that consist of combinations of oral and intravenous anticancer drugs have been developed . examples of such oral agents are lv and uft , which are recommended in the japanese colorectal cancer treatment guidelines . the active metabolite of this drug , fdump , forms complexes with thymidylate synthase ( ts ) and inhibits its activity , thereby inhibiting dna synthesis and suppressing tumor growth . in addition , the active metabolite of lv , 5,10-ch2-thf , forms strong complexes with fdump and ts , thereby delaying the dissociation of ts and further intensifying the antitumor effect of uft . the administered dose of lv differs depending on the protocol employed , but the response rate does not necessarily show dose dependence . in addition , the effective concentration of 5,10-ch2-thf differs as a function of the duration of contact and has been reported to be 1 m as well as 10 m . the commonly used doses of lv and uft have been , respectively , 75 mg / day and 250300 mg / m / day ( both administered in three divided doses per day ) . however , etienne - grimaldi et al .   took into consideration patient convenience and investigated the auc in the case of twice daily administration . they reported that administration in two divided doses per day resulted in aucs for fluorouracil and uracil that were approximately two - fold those in the case of administration in three divided doses per day . in addition , hoff et al .   carried out a phase ii clinical study of lv ( 50 mg / day ) and uft ( 250300 mg / m2/day ) administered in two divided doses per day and reported that both efficacy and safety were equivalent to administration in three divided doses per day . .   added irinotecan to the lv / uft combination and reported that it showed greater efficacy than lv / uft alone , while safety was also maintained . based on those findings , we devised and were the first to test the mtegafiri regimen . in the present patient , mtegafiri chemotherapy to treat unresectable , multiple liver metastatic lesions caused only mild adrs while achieving cr . to date we therefore consider mtegafiri chemotherapy to be a potentially useful treatment option for patients with unresectable , recurrent colon cancer .
we report the case of a patient with colon cancer accompanied by multiple unresectable liver metastases who showed complete response ( cr ) to modified tegafiri ( mtegafiri ) ( tegafur - uracil / leucovorin+irinotecan ) chemotherapy . 
 the patient was a 58-year - old japanese male with cancer of the descending colon accompanied by multiple unresectable liver metastases . 
 following resection of the sigmoid colon cancer , mtegafiri chemotherapy was administered . abdominal computed tomography 
 performed upon completion of 12 courses of chemotherapy showed that the unresectable liver metastatic lesions had disappeared , indicating cr . 
 the only adverse drug reactions ( adrs ) experienced to date have been stomatitis ( grade 1 ) and neutropenia ( grade 1 ) . 
 anticancer therapy has thus been continued , and cr has been maintained for 15 months . 
 the present patient achieved cr in response to mtegafiri chemotherapy , a regimen that has not previously been reported , while experiencing only mild adrs and maintaining a good quality of life . 
 mtegafiri chemotherapy is convenient to administer and is thought to be a potentially useful treatment option for patients with unresectable , recurrent colon cancer .