The image is a screen grab from a video the two starred in for the 2014 White House Correspondents Dinner, where Louis-Dreyfus (in character as Selina Meyer) and Biden got up to shenanigans in Washington D.C.
The Veep star tweeted a message back, thanking Biden.
The 56-year-old actress revealed her diagnosis on Twitter, writing, "1 in 8 women get breast cancer. Today, I'm the one. The good news is that I have the most glorious group of supportive and caring family and friends, and fantastic insurance through my union."
"The bad news is that not all women are so lucky," she added. "So let's fight all cancers and make universal healthcare a reality."
For more on Louis-Dreyfus' diagnosis, watch the video below.