Well, from my point of view this chip is simply a very sensitive protein quantification device. You can measure a wide range of proteins (related to cardiac disease, allergies, Alzheimer's, and many more), not just "cancer biomarkers", i.e. proteins which are suspected/proven to have a link to cancer.
How reliably can one really diagnose cancer from a blood protein test? In my opinion, cancer has so many different forms (it mutates constantly) that it is harder to find a common and highly reliable diagnostic marker for it than it is for many other diseases.
For that reason, right now a definite cancer diagnosis is still made by physically finding the tumor tissues, I think. However, there will probably be enough data to perform a high confidence diagnosis from blood tests in the near future.
The chip mentioned here could speed up research and adoption of protein tests into general medicine.
As a little mini-overview over biomarkers:
Mostly Established:
Pregnancy: hCG (human chorionic gonadotropin) is a high-confidence biomarker
Cancer: CEA (cancer embryonic antigen) was used in the mouse model in the Nature paper
Prostate Cancer: PSA (prostate-specific antigen) used to be highly regarded, now somewhat disputed
Heart disease: Troponin-I is a very specific marker of heart tissue damage
Upcoming (i.e. prospective biomarkers have been identified but need to be validated):
Alzheimers
Autoimmune Diseases
Etc. (Lots of research going on).