Grading of breast cancer

1. A method of treating breast cancer in a human subject, said method comprising

assaying a sample from the human subject for gene expression levels of CENPA (centromere protein A (17 kD), chromosomal location 2p24-p21), RACGAP1 (Rac GTPase activating protein 1, chromosomal location 12p13.2-p13.1), RRM2 (ribonucleotide reductase M2 polypeptide, chromosomal location 2p25-p24), and NEK2 (NIMA (never in mitosis gene a)-related kinase, chromosomal location 1q32.2-q41);

determining a measure of similarity between the gene expression levels of the human subject and reference gene expression levels for a reference population of cancer subjects; and

either (a) treating the human subject with an antitumor agent, chemotherapy, or surgical removal of cancer tissue if the measure of similarity is above a threshold; or (b) conducting a cytological examination of cells from the human subject if the measure of similarity is above the threshold.

2. The method of claim 1 wherein said assaying comprises amplifying RNA from said sample.

3. The method of claim 2 wherein amplifying said RNA comprises quantitative PCR amplification.

4. The method of claim 2 wherein amplifying said RNA comprises reverse transcription PCR (RT-PCR).

5. The method of claim 1 wherein said assaying comprises determining gene expression levels by array hybridization.

6. The method of claim 1 wherein said sample is a ductal lavage, needle biopsy, surgical biopsy, or fine needle aspirate sample.

7. The method of claim 1 , wherein said sample is microdissected to isolate one or more cells suspected of being breast cancer cells and said assaying is of RNA in said isolated cells.

8. A method of treating breast cancer in a human subject, said method comprising

assaying a sample from the human subject for gene expression levels of CENPA (centromere protein A (17 kD), chromosomal location 2p24-p21), RACGAP1 (Rac GTPase activating protein 1, chromosomal location 12p13.2-p13.1), RRM2 (ribonucleotide reductase M2 polypeptide, chromosomal location 2p25-p24), and NEK2 (NIMA (never in mitosis gene a)-related kinase, chromosomal location 1q32.2-q41);

comparing the gene expression levels of the human subject to corresponding reference gene expression levels for a reference population of cancer subjects; and

either (a) treating the human subject with chemotherapy if the gene expression levels of the human subject are higher than the corresponding reference gene expression levels, (b) conducting a cytological examination of cells from the human subject if the gene expression levels of the human subject are higher than the corresponding reference gene expression levels, or (c) administering a breast cancer treatment other than chemotherapy if the gene expression levels of the human subject are lower than the corresponding reference gene expression levels.

9. The method of claim 8 wherein said assaying comprises amplifying RNA from said sample.

10. The method of claim 9 wherein amplifying said RNA comprises quantitative PCR amplification.

11. The method of claim 9 wherein amplifying said RNA comprises reverse transcription PCR (RT-PCR).

12. The method of claim 8 wherein said assaying comprises determining gene expression levels by array hybridization.

13. The method of claim 8 wherein said sample is a ductal lavage, needle biopsy, surgical biopsy, or fine needle aspirate sample.

14. The method of claim 8 wherein said sample is microdissected to isolate one or more cells suspected of being breast cancer cells and said assaying is of RNA in said isolated cells.

15. The method of claim 1 , wherein the human subject is treated with chemotherapy if the measure of similarity is above the threshold.

16. The method of claim 8 , wherein the human subject is treated with chemotherapy if the gene expression levels of the human subject are higher than the corresponding reference gene expression levels.