Staging and grading

Staging

The estimation of the extent of disease (of both primary and metastatic tumours). Aids in treatment planning, prognosis, and evaluation of treatment modalities.

Staging systems

Describe whether or not, and to what extent spread has occured. Considering size of primary, involvement of local structures, spread via lymphatics, presence of absence of distant metastases.

Critea of staging system

Be able to be used for all tumours and sites. Be simple to use and interpret. May not be available in less developed countries. Not be dependent on complex investigations. Criteria for each stage must be set out in a logical progression from the least to the greatest involvement.

TNM System

Most commonly used staging system. Each letter has a number suffix ranging from 0-4. Number indicates degree of involvement.

T= Tumour

Reffers to primary tumour size, depth and growth. TX= tumour cannot be measured. T0= no evidence of primary tumour. T(is)= cancer cells growing in most superficial layer of tissue with no growth into deeper layers.

N= Node (lymph)

N1= mobile nodes on ipsilateral side as primary. N2=1 N2= mobile nodes on contralateral side of primary. N3= spread to more distant or numerous involved nodes.

M= metastases

Absence or presence of metasteses. M0= absent. M1= present.

Clinical staging vs pathological staging

cTNM based on evidence aquired before treatment from physical examination, radiological studies and biopses. pTNM based on evidence evidence aquired from surgical procedure, surgical exploration or pathological examination.

y,r,a TNM

yTNM= stage assessed after chemo/ RT. rTNM= stage for reccurent tumour after period of time disease free. aTNM= stage determined at autopsy (after death).

Stage grouping

Tumours can be grouped into stage 0-4. Ensures each group is homogenous in sense of survival.

Other staging systems

CNS cancers staged according to their cell type and grade. Blood or bone marrow is more a systemic disease so no staging system. FIGO used for cervix, uterus, ovary, vagina, and vulva cancers. Some childhood cancers use COG criteria.

Grading

Well differentiated tumours resemble parent tissue and easily recognisable. Undifferentiated tumours are messy and dont resemble parent. Tumours are graded based on degree of malignancy, ranging from 1-4.

Four tier grading system

grade 1= well differentiated. grade 4= undifferentiated. Higher grade= more likely to be malignant.

Grading importance

To determine likely behaviour of tumour (high grades less curable). Help determine treatment choice. Higher grade= worse prognosis

Gleason scoring

Biopsy samples are graded (1-5) to show activity of prostate cancer. Grade 1-2 very rarely found. Malignant tumours graded 3-5. More than 1 grade of cancer, so the grade of 2 most common patterns in biopsy sample are added to give Gleason score with the most common being first.

ISUP grouping

Enhanced from gleason score. Simpler with 5 grades