A breakthrough study published last week showed that some breast cancer patients don't need to have cancerous lymph nodes under their arms removed. That is great news for the estimated 20 percent of patients who will avoid an invasive surgery that can cause chronic swelling in the arm. But, as with most cancer breakthroughs,  there are people left behind.

Dr. Julia Tchou, a breast cancer surgeon with the University of Pennsylvania, said she got a lot of calls from concerned patients the morning after the news broke.

"What does this study mean? What do I do, does it mean that I don't need more surgery?,” Tchou said her patients asked. “I really  have to clarify what the study results mean."

Tchou said many patients didn’t understand that the study applied only to a relatively small subset of breast cancer patients: early onset patients with small tumors, no metastases to other parts of the body and no palpable lymph nodes. Tchou said a few of her patients who called would likely be able to cancel upcoming surgeries; for the rest, the study’s results would have no effect.

Coleen Boyd, a social worker at the Fox Chase Cancer Center, has been seeing women through breast cancer treatments for 20 years. The first thing she mentions when asked about the study are the patients who already had  their lymph nodes removed.

"They're like, ‘Now it's coming out that it didn't need to be done.’” Boyd said.

Boyd said the reaction is common as breast cancer treatments get more targeted and less invasive. She guesses the same thing happened when mastectomies started to give way to lump removals in the 1980s. Boyd said every time a new drug or treatment makes the news, every patient wants to see if it's right for her.

"Everyone wants to know, is this something I can do, and it's great when you are a candidate,” Boyd said. “It’s harder when this new stuff comes out and it's all over the place and you have to tell her no, you're not a candidate for this."

New treatments are wonderful for those who they can help, but they can raise false hopes for people they won't help, she said.