Inclusion Criteria:

- Pathological/ cytological diagnosis of adenocarcinoma of the rectum. Patients must
have operable rectal cancer that is amenable to surgery.

- No prior therapy for rectal cancer

- Eastern Cooperative Oncology Group (ECOG) Performance status 0 or 1

- Adequate organ function

- Patient compliance and geographic proximity that allow adequate follow-up

- For women: Must be surgically sterile, postmenopausal, or compliant with a medically
approved contraceptive regimen during and for 3 months after treatment; must have a
negative serum or urine pregnancy test and must not be lactating.

- For men: Must be surgically sterile or compliant with a contraceptive regimen during
and for 3 months after treatment.

- Estimated life expectancy of at least 12 weeks

- Signed informed consent

- At least 18 years of age

Exclusion Criteria:

- Concurrent administration of any other anti-tumor therapy.

- Treatment within the last 30 days with a drug that has not received regulatory
approval for any indication at the time of study entry.

- Serious concomitant systemic disorders (e.g., active infection including HIV, cardiac
disease) that in the opinion of the investigator would compromise the patient's
ability to complete the study.

- Have previously completed or withdrawn from this study or any other study
investigating pemetrexed.

- Are pregnant or breast-feeding.

- Second primary malignancy that is clinically detectable at the time of consideration
for study enrollment.

- History of significant neurological or mental disorder, including seizures or
dementia.

- Inability to interrupt aspirin or other nonsteroidal anto-inflammatory drugs (NSAIDs)

- Presence of clinically relevant third-space fluid collection that cannot be
controlled by drainage or other procedures prior to study entry.

- Inability or unwillingness to be given 5,10-methylenetetrahydrofolate, vitamin B12 or
dexamethasone.