The purpose of these pages is to provide surgeons with the ability to calculate the probability of lymph node metastases using the St Mark's Lymph Node Positivity Model for patients undergoing local resection of rectal cancers and for patients whose nodal harvest was not sufficient to adequately stage the rectal cancer.

There is also a wealth of general information on risk prediction in surgery - this area of the site is constantly being updated and it is worth checking back on a regular basis. The service described above is provided free of charge with no liability attached.

This model has been presented at the American Society of Colon and Rectal Surgeons (ASCRS) scientific meeting at Dallas Texas, May 2004.


Calculate the St Mark's LNP Score

Choose a value in each category that matches your patient from the drop down lists describing the patient and histopathological criteria. Default values are shown for each category. Simply submitting the form as it is without changing the values (i.e. a young fit patient having s T1 well differentiated adenocarcinoma without any vascular or perineural invasion and conspicuous lymphocytic infiltration) still gives a % risk for lymph node metastases.


Depth of invasion (T-stage)
Histological type
Lymphocytic infiltration
Vascular invasion
Perineural invasion