With over 2 million new breast cancer cases each year, there is a keen need for treatments that improve survival for patients with this disease. Completion of the Human Genome Project in 2003 is often considered as the launch of precision medicine, but the breast cancer field pioneered targeted therapy several years earlier, in 1998.
It seems self-evident that cancer treatment should selectively seek out rogue, cancer-promoting molecules exclusively in tumor cells rather than indiscriminately killing all dividing cells. This is precisely the premise that Virginia Kaklamani, MD, DSc, described in her plenary session on Tuesday, “Using Biomarkers to Tailor Treatment for Breast Cancer.” She noted that the goal of targeted or tailored therapies is to specifically stop proteins that promote tumor cell proliferation and survival.
Keeping track of the many different therapies and biomarkers used to treat breast cancer can be daunting. Kaklamani’s primary objective is for people to recognize that precision medicine is progressing in breast cancer such that treatment “can now be individualized for patients based on their genetic and genomic makeup.”
One reason for the array of tailored therapies is that breast cancer isn’t a single entity. The many distinct types of cancer require that tumor subtype be known to tailor treatment for each patient. For example, cancers with estrogen or progesterone hormone receptor expression—or both—are classified as ER+ or PR+ breast cancer. So-called triple negative breast cancer lacks estrogen, progesterone, and HER2 protein. This type of breast cancer is notable because few tailored therapies for it exist, and it therefore carries a less favorable prognosis.
The availability of multiple tailored treatments means that oncologists must identify which patients will benefit from each. Guess who they turn to in this venture? In Kaklamani’s view, “the laboratory is more and more important” for selecting which patients are candidates for specific treatment types. Oncologists rely on multiple pathology specialties, including anatomic pathology as well as hematology, chemistry, immunology, and genomics laboratories, to create comprehensive and tailored treatment plans.
Keeping in mind that cancer arises from deregulation of normal checks and balances on cell proliferation, some tumors inevitably will become resistant to targeted therapies. This is yet another opportunity for laboratories to support oncologists, as resistance can often be detected at a molecular level before clinical symptoms manifest. Excellent communication between laboratories and oncology teams is important to guide appropriate use of combination therapy or more aggressive therapy.
Much work remains in optimizing our ability to tailor candidate treatments for individual patients. However, as tailored therapies become more integrated in cancer care so too does the need for strong partnerships between laboratories and oncology providers.