Trial Information

the Effect of the Preoperative Short-course Radiotherapy for the cT3/cN+ Mid-lower Rectal Cancer: a Prospective Randomized Study

The colorectal cancer is the secondary most common cancer among the population. Every
year,it's estimated that there was over 1,200,000 new cases,and in China the data is about
440,000. The local recurrence (LR) and the lung or liver metastasis are the most critical
problems that confusing the doctor,which the local recurrence rate is about 3%-50%,with a
median rate of 18.8%。 Now, multidisciplinary treatment become a standard treatment for the
rectal cancer, and the preoperative adjuvant chemoradiotherapy is a critical part of the
therapy. As various trials have confirmed that the preoperative chemoradiotherapy can reduce
the postoperative local recurrence rate. And,there are two kinds of preoperative adjuvant
therapy,the long-term chemoradiotherapy and the short-term radiotherapy. In the US, the
long-term is more common,with a total dose of 50.4 Gy in 25-28 fraction,and in the Europe,
the short-term are more common with a dose of 25 Gy in 5 fraction.For the two,there is no
conclusion about which is better. The National Comprehensive Cancer Network(NCCN) guideline
recommend that for the patients with preoperative stage T3N0，or T1-3N1-2,preoperative
radiotherapy is necessary.However the Polish Colorectal Study Group found that there is no
difference in survival, local recurrence or late toxicity,in the short-term
radiotherapy,with a less Early radiation toxicity.So that the short is more regarded.

Although the preoperative radiotherapy can decrease the local recurrence, it can't increase
the 5-year survival. The reason for the radiotherapy reducing the local recurrence was that
the radiation decreased the positive rate of the circumferential resection margin(CRM) of
the total mesorectal excision(TME) operation. In a recent prospective trial in UK, the
preoperative adjuvant radiotherapy can decrease the local recurrence with different
operation quality(both completed TME or uncompleted TME), however a defect of this trial was
that the lymph node positive patients were not receiving the postoperative supplementary
radiation.

One of the other factors influencing the LR is the operation quality, completely resection
of the mesorectum can decrease the LR to about 4%. As the obesity can influence the TME, in
the Asia the experienced surgeon can have a higher rate of mesorectum resection,in the
thinner asian.

Overall, for the patients that the tumor have not invaded the mesorectum and the operation
has a completely resection of the mesorectum, the preoperative adjuvant radiotherapy may
have no difference with the selective postoperative chemoradiotherapy. In addition to
this,the preoperative adjuvant therapy can induce various complications,injury of the
nervous plexus, radical rectitis,increasing the infection rate of the wound. About 5%-10%
radioresistant patients has the carcinoma enlarged or metastasis during the adjuvant
treatment.

So that,dividing the T3 patients into subgroups, that for the CRM may positive or the lymph
node may positive,the preoperative radiotherapy may be positive, and for the preoperative
negative CRM and no lymph node metastasis,the radiotherapy may have a negative effect. This
trial was mainly focus on the patients whose preoperative stage was T3 or N+. The patients
which included will be divided in to 2 subgroup according the preoperative CT and Endoscopic
ultrasound,the early mesorectal involvement group (EMRI): the tumor invade into the
mesorectum<=5mm,or the hole bowel in the peritoneum covering part; in the anterior wall ,the
tumor had not invaded into the fat tissue; there is no high-density image in the mesorectum
in the CT scan; there is no enlarged lymph node that larger than 8mm; if the preoperative
stage is T1-3N+,the lymph node <=8mm; and the late mesorectal involvement group (LMRI): the
tumor invade into the mesorectum >5mm, in the lateral or posterior part. There is
high-density image in the mesorectum in the CT scan; there is enlarged lymph node which is
larger than 8mm; the tumor invade the whole circle of the bowel by anal examination;and
carry out randomized trial in the two groups individually. The purpose of this trial is to
confirm whether the preoperative radiotherapy is necessary for the EMRI patients,identify
the reason of the local recurrence,and finally help the making of the treatment decision for
the advanced resectable rectal cancer.