A study suggests women diagnosed with small, early-stage, HER2-positive breast cancers -- smaller than 1 cm (about 4/10s of an inch) -- that have not spread to lymph nodes may get benefits from receiving Herceptin (chemical name: trastuzumab) after surgery. About 10% of breast cancers are HER2-positive, smaller than 1 cm, and have not spread to the lymph nodes.
HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. HER2-positive breast cancers tend to be more aggressive and harder to treat than breast cancers that are not HER2-positive.
Herceptin is a targeted therapy and treats HER2-positive breast cancers by attaching to the HER2 protein and blocking that protein from receiving growth signals. Herceptin, which is given intravenously, is approved by the U.S. Food and Drug Administration to:
- treat advanced-stage, HER2-positive breast cancers
- lower the risk of recurrence (the cancer coming back) of early-stage, HER2-positive breast cancers with a high risk of recurrence
When medicine is given after other treatments to reduce the risk of recurrence, it's called adjuvant treatment.
Herceptin is not used routinely to reduce the risk of recurrence of early-stage, HER2-positive breast cancers that are smaller than 1 cm, especially if the cancer hasn't spread to the lymph nodes. This is because the risk of recurrence of these types of breast cancers is relatively low. Most doctors believe that using Herceptin as an adjuvant treatment won't really change the risk of recurrence of these small, early-stage cancers. Still, some research suggests that Herceptin may meaningfully reduce the risk of recurrence of small, early-stage HER2-positive breast cancers.
In this study, researchers analyzed the results of other studies on Herceptin and recurrence risk for HER2-positive breast cancers, looking very carefully for evidence that adjuvant Herceptin treatment might be beneficial, even if the cancer is small.
The researchers found that fewer than 10% of women with HER2-negative breast cancers smaller than 1 cm that hadn't spread to any lymph nodes had a recurrence in the 10 years after first diagnosis. Still, the risk of recurrence remained for decades after diagnosis:
- overall, 16% to 17% of the women had a recurrence 1 to 15 years after initial diagnosis
- overall, 21% to 29% of the women had a recurrence 1 to 20 years after initial diagnosis
They also found that small, high-grade, HER2-positive breast cancers are more likely to come back compared to those that are low grade. In the pathology report, doctors assign a numerical grade to cancer cells (1, 2, or 3) based on how different they are compared to normal breast cells. Grade 1 cells look closest to normal and grade 3 cells look the least like normal breast cells. In general, the higher the cancer grade, the more aggressive the cancer (grows faster, is harder to treat, more likely to come back).
The researchers' analysis of several studies on the benefits of adjuvant Herceptin to treat large and small HER2-positive breast cancers found that women diagnosed with small HER2-positive breast cancers got some benefit from Herceptin compared to women diagnosed with small HER2-positive breast cancers who didn't get adjuvant Herceptin. This was true even when the cancer hadn't spread to the lymph nodes.
The researchers concluded that doctors should consider using adjuvant Herceptin to reduce the risk of recurrence in women diagnosed with HER2-positive breast cancers smaller than 1 cm that haven't spread to the lymph nodes more often. Current treatment guidelines don't recommend routinely using adjuvant Herceptin to the reduce recurrence risk of these small HER2-positive breast cancers. Still, the researchers feel that Herceptin can meaningfully reduce the risk of recurrence, especially when:
- the cancer is bigger than 0.5 cm
- the cancer is grade 2 or 3
If you've been diagnosed with a small, early-stage, HER2-positive breast cancer and you and your doctor are planning your treatment, you may want to discuss this study and ask if adjuvant Herceptin makes sense for you.
You can learn more about Herceptin in the Breastcancer.org Targeted Therapies section.