Cowboy-
OK, I'm not pulling any punches here, so be ready.
There appears to be a convergence of B-cell diagnoses when you get up into the really aggressive forms: there's the most preferable one, which we might call your everyday average DLBCL. preferable because the most is known about it, because treatments are known to work well, etc.
there's also Burkitt's. Dr. Judith Ferry (a pathologist with Harvard and Mass General) wrote in the journal The Oncologist in 2006 that "Among human neoplasms, [Burkitt's] has the shortest doubling time." In other words, it grows faster, or is more aggressive, than any other known cancer. I knew Burkitt's was up there, but I wouldn't have guessed that it was number one.
Then there's what you mentioned, "double hit", which as a term was 100% new to me. Also called 'dual fusion', what 'double hit' means is that the lymphoma subtype has so-called "dual gene translocations" and these are what you mentioned, the MYC and the Bcl2. So it's often referred to as either MYC/BCL2 (or M/B) high-grade B-cell lymphoma. It could have evolved from a previous B-cell lymphoma or appeared on its own out of nowhere. Extranodal involvement is not uncommon, and it's not uncommon to relapse or for the disease to be refractory (as your onc has mentioned). The reason it's believed to be so fucking aggressive is because of the meeting of those two translocations—MYC promotes rapid proliferation, or speedy growth, while BCL2 discourages (for lack of a better word) apopotosis, or the kind of programmed cell death that every cell is supposed to go through, but do not go through when cancerous.
So you ask if those markers improve your situation, the straight up answer is no.
You might be wondering just how they're coming to all these minute conclusions when it seems like it would be fairly straightforward-- either it's Cancer X or it's not. But lymphomas are not like that. Several decades ago, someone made a huge mistake: they started grouping cancers that affect the lymphocytes under the same banner, 'lymphoma'. this is a mistake because so many of the dozens of lymphoma subtypes are known to be heterogenous- or totally different- cancers from one another.
I wrote about the huge obstacles facing pathologists in lymphoma a month or two ago ("A tale of two t-cells"), and those two pictures I included illustrate the problem; they look pretty fucking similar, but they are as different as night and day. So in order to make diagnoses and treatment modalities more accurate in lymphomas, pathologists now need to tease out what molecular markers are expressed on the cell surface-- which is why we tell everyone diagnosed with lymphoma to get a second opinion from a qualified blood pathologist at a national comprehensive cancer center (NCCN) because an average pathologist lacks the experience.
If interested, go to PubMed's home (http://www.ncbi.nlm.nih.gov/pubmed/) and enter this in the search field, "Tibiletti MG Hum Path". You should land on a 2009 paper about the clinical relevance of BCL2, MYC, and three other rearrangements in diffuse large B-cell lymphoma. It's just an abstract. But it's plenty.
The last thing to keep in mind here is that whether it's Burkitt's, Burkitt's-like, or DLBCL, every source says the same thing-- they're curable. this is likely due to their aggressiveness and the fact that this is what combination chemo was made for.
Ross