28 Sep Dr Yael Mark – Rectal Cancer: Pros and Cons of Neoadjuvant Therapy and Indications for Adjuvant Therapy
Surgical excision is considered to be essential for the curative treatment of rectal cancer, however, the addition of chemotherapy and radiotherapy in either the neoadjuvant or adjuvant setting play an important role in the treatment of locally advanced rectal cancer.
Neoadjuvant chemo-radiation is the preferred treatment in advanced rectal cancer, as per the results of the German Rectal Cancer Trial1. This trial compared pre-operative and post-operative CRT in patients with T3/T4 or node positive rectal cancer.
Although there was no difference in overall survival between the neo-adjuvant or adjuvant therapy groups, pre-operative therapy was associated with improved local control. The group that received pre-operative therapy had a local relapse rate of 6% versus the post-op group who had a local relapse rate of 13%. Post-operative complication rates were the similar in both groups.
Advantages and Disadvantages of Neoadjuvant Therapy in Rectal Cancer
- Improves resectability in locally advanced disease
- Reduces the risk of locoregional recurrence after surgery
- Reduces the risk of treatment associated toxicity. Treatment fields are often smaller especially for patients requiring AP resections.
- Irradiating tissue that is surgery naïve and thus better oxygenated may lead to greater radiotherapy sensitivity
- May increase chances of a sphincter sparing procedure in patients with a low lying tumour
- Can assess the tumours response to chemo-radiotherapy to help to tailor future therapies
- Possible over-treatment of patients with early stage disease or undetected metastases.
- Clinical staging using imaging and examination is less accurate then pathological staging. There is therefore a risk of over-treatment of disease that has been clinically over or under staged.
- The German Rectal Cancer Trial showed that 18% of patients staged by endo-rectal sonar as having T3 or node positive disease had node negative disease confined to the rectal wall on later pathological assessment1.
Rectal Cancer- Indications for Adjuvant Therapy
In cases where primary surgery has been performed, the following factors are indications for adjuvant therapy:
1) T3 disease – tumour extending through the muscularis propria into the perirectal tissue.
2) T4 disease- tumour penetrating the surface of the visceral peritoneum (T4a), tumour directly invading into or adherent to adjacent organs or structures (T4b).
3) Positive resection margins
4) Node positive disease.
In these cases, post-operative chemo-radiation has been shown in multiple phase III trials to be associated with improvements in both disease free and overall survival rates.2,3
Dr Yael Mark
28 September 2017
- German Rectal Cancer Study Group, Sauer et al, 2004
- GITSG 7175 (Thomas and Lindblad, 1988)
- NCCTG 79-47-51 (NEJM 1991)