This is a double-blind, randomized, placebo-controlled, parallel study. The main goal is to investigate the auxiliary effects of Fucoidan for the patients with locally advanced rectal cancer who receive neoadjuvant CCRT before surgery. The quality of life is our primary endpoint for this study. The study is an observational study.

Inclusion Criteria:

1. Age was more/equal to 20 year-old and less/equal to 80 year-old
2. Diagnosed as locally advanced rectal cancers by pathological biopsy and image study.
3. ECOG performance status within 0 to 2 points
4. Excepted life remaining at least 4 months
5. Females with fertility are willing to use effective contraception during the period of study
6. Willing to follow the test procedures and tracking procedures
7. sign the inform consent form

Exclusion Criteria:

1.Suffering from other primary malignant tumors 2.Females who are pregnant, planning to become pregnant, or breastfeeding 3.Participate in other interventional clinical trial within the first 30 days 4.Suffering from major mental illness such as mental retardation and mental disorders 5.Unable to understand and answer research questions (oral or written) 6.Abnormal laboratory data within 14 days before joining the study 7.Evidence that subject has a severe or uncontrolled disease

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we enrolled the patients with locally advanced rectal cancers and received neoadjuvant CCRT (concurrent radiochemotherapy) before.