There are many good alternatives. You could use
- Biomart through http://www.ensembl.org to export a list of SNPs in the promoters of genes (attributes) and filter it by your oncogene gene identifiers (if you have such a list, or can generate it).
- The snpEff tool through https://usegalaxy.org is another alternative.
- Ensembl variant effect predictor http://useast.ensembl.org/info/docs/tools/vep/index.html (There's a web version as well as a download.
If you are also interested in SNPs with potential regulatory effect that are outside of the promoter, you can explore:
ANNOVAR annotates disruptions of conserved transcription factor binding sites
FunSeq gives scores for non-coding variants, but I personally prefer the ANNOVAR report.