Bring a large pot of salted water to a boil. Add the pasta and cook as the label directs for al dente. Reserve 1 cup cooking water, then drain.
Meanwhile, heat the olive oil in a large skillet over medium-high heat. Add the garlic and cook until browned, 1 minute. Add the pancetta and anchovies and cook, stirring, until browned, about 2 minutes. Remove from the heat and add the clams, then stir in the wine. Cover and cook over high heat until the clams open, 5 to 6 minutes. Remove the clams to a large bowl (discard any clams that do not open). Cover to keep warm.
Add the chicken broth to the skillet and cook until slightly reduced, about 3 minutes. Add the pasta to the skillet along with 1/2 cup of the reserved cooking water. Simmer, tossing, until the pasta is well coated and the sauce thickens slightly, 1 to 2 minutes. Add more cooking water to loosen, if needed. Stir in the clams and any juices. Add the parsley, red pepper flakes and lemon juice; season with salt. Divide among bowls.