Systemic Therapy and Combination Therapy for Rectal Cancer





Patients with stage I rectal cancer are highly likely to be cured only with resection.



オキサリプラチン  oxaliplatin

括約筋  sphincter

カペシタビン  capecitabine

筋層  muscular layer

切除端面が陰性と陽性の中間である  close margin

直腸間膜全切除  total mesorectal excision

粘膜下組織  submucosa

フルオロピリミジン  fluoropyrimidine



Since it is difficult to achieve negative resection margins of rectal cancer, patients need to receive radiation therapy. 



If they are positive, the risk of local recurrence of rectal cancer becomes high. 



When patients with stage I rectal cancer undergo standard resection surgery, they generally do not need to receive additional treatment .


However, If recurrence risk of rectal cancer is high in patients who underwent resection surgery (tumor extending muscular layer; tumor staying in submucosa with poorly differentiated histology, perineural or lymphovascular invasion, or close margins), they need to receive postoperative pelvic irradiation with or without 5-FU chemotherapy, or undergo total mesorectal excision.


credit:  Oxaliplatin, anti-cancer drug, Fujifilm Phama Co., Ltd.



Patients with stage II or III rectal cancer normally receive radiation therapy as standard regimen to decrease recurrence rates of rectal cancer, increase the likelihood of sphincter preservation, and improve survival rates.



When radiation therapy is performed, timing (pre-or postoperative use), course (short or long), and combination chemotherapy using fluoropyrimidine need to be carefully considered. 



If shrinkage of rectal cancer is not required, patients need to be treated with a short course (5 days) of preoperative radiation therapy without chemotherapy.


When patients are treated with a short course of radiation therapy, they still need to receive postoperative systemic therapy, with either a fluoropyrimidine alone (stage II) or a fluoropyrimidine-oxaliplatin combination regimen (node-positive disease), to minimize the risk of distant metastases of rectal cancer.



When shrinkage of rectal cancer is necessary to easily and effectively remove it, patients need to be treated with a long course (around 5.5 weeks) of radiation therapy. 



Patients are normally treated preoperatively or postoperatively with a long course of radiation therapy in combination with 5-FU or capecitabine  if they were not treated preoperatively with a short course of radiation therapy.



Since oxaliplatin has higher toxicity and its preoperative use does not improve treatment result, it is not recommended to be preoperatively used.



However, if the rectal cancer has metastasized to lymph nodes, oxaliplatin may be used postoperatively.


When patients with rectal cancer are treated with a long course of radiation therapy, since the toxicity of  preoperative use of oxaliplatin weakens compared with its postoperative use, they are expected to have good outcome. 



However, because of toxicity of oxaliplatin's preoperative use for patients with stage I rectal cancer, they should be accurately staged to prevent them from preoperatively taking the drug. 



Patients with rectal cancer thought to be at low risk of local recurrence (grow to pericolorectal tissue but node negative; grow to submucosa or muscular layer with regional node positive) may undergo total mesorectal excision plus systemic therapy without postoperative radiation therapy.