Pathology report/Pathological staging

[paknee]

I had a TT 2/17/15.  Follow up with surgeon 3/4 and was told 5 of 7 central neck lymph nodes are + for PTC.  My pathology report is as follows:
TT, pretracheal node biopsy, central neck dissection (all of which are + for PTC)
Tumor focality : unifocal
Tumor laterality: left lobe and isthmus
Tumor size: 1.2cm
Histologic type: papillary carcinoma
   Variant: classical
   Architecture:  classical
   Cytomorphology: classical
Margins: Focally involved by tumor
Lymphovascular space invasion: present
Extrathyroidal extension: not identified
Additional pathologic findings: benign parathyroid gland
Lymph nodes:
   Number examined: 9
   Number involved: 7

Pathologic stage: pT1bN1R1

Okay so "unifocal and classical" sound good. What does the Margin information mean?  What are the 7 of 9 lymph nodes involve at end of report mean?  What in the world does the "R" stand for?  I know I am considered Stage lll because of my age, tumor size and lymph node involvement but all the literature I have read refers to "M" not "R" so does this mean they believe it has spread to lymph nodes in other areas of my body?  I don't see the radiation oncologist until 3/11 but the hospital sent me a generic video session on external radiation.  The surgeon only mentioned oral radiation.  All opinions/information appreciated.  Thank you in advance.

[Red_Star]

Radiation beam therapy is typically used when later stage thyroid cancer has not responded to radioactive iodine therapy (either liquid or pill form).

[Red_Star]

Residual means remaining or left over. In other words your TT did not remove all of the thyroid tumour.  Radioactive iodine is used to eliminate any residual thyroid or thyroid cancer cells.

[paknee]

Red_Star, Thank you so much!  Can you tell me what residual tumor means?

[Red_Star]

Residual Tumour (R) Classification.

RX: Presence of residual tumour cannot be assessed
R0: No residual tumour
R1: Microscopic residual tumour
R2: Macroscopic residual tumour