Diagnosis and prognosis of breast cancer patients

A method for classifying a cell sample as BRCA1-related or sporadic, comprising

• (i) calculating a measure of first similarity between a first expression profile and a BRCA1 template and a second measure of similarity between said first expression profile and a non-BRCA1 template;
• said first expression profile comprising the expression levels of a first plurality of genes in said cell sample;
• said BRCA1 template comprising, for each gene in said first plurality of genes, the average expression level of said gene in a plurality of BRCA 1 patients;
• and said non-BRCA1 template comprising, for each gene in said first plurality of genes, the average expression level of said gene in a plurality of non-BRCA1 patients, said first plurality of genes consisting of at least 5 of the genes for which markers are listed in Table 3;
• (ii) classifying said cell sample as BRCA1 if said first expression profile has a higher similarity to said BRCA1 template than to said non-BRCA1 template, or classifying said cell sample as sporadic if said first expression profile has a higher similarity to said non-BRCA1 template than to said BRCA1 template;
• and
• (iii) displaying;
• or outputting to a user interface device, a computer readable storage medium, or a local or remote computer system;
• the classification produced by said classifying step (ii).