There are a lot of misconceptions about the Holman Pathway. Since so many applicants are asking about it, I may as well put it in the FAQ. In the meantime, here are the answers to your questions:
Is it difficult to obtain the Holman Pathway? If so, why?
It depends how you define "difficult." If your definition is the number of applicants accepted into the Holman pathway divided by the number who apply then the answer is no, it is not difficult as the value is close to 1.0.
If you define "difficult" as (a) matching at a residency that is actually receptive to residents doing the Holman pathway (very few), (b) finding a mentor who is willing to take you on, (c) having a residency that is willing to tackle the hardships of having a resident mostly out of the clinic for 18-21 months then the answer is yes, it is difficult to get all of your ducks in a row.
I imagine it is more troublesome to assimilate the Radiation Oncology knowledge base when faced with other committments, to what extent is this true? Do you think the Holman pathway detracts from clinical competency?
This is a controversial question. If you ask non-Holman residents (the vast majority of Rad Onc residents) the answer to them would be an obvious "yes it detracts from your clinical competency." Maybe even, "hell yes! It detracts from your clinical competency."
As a resident who has completed the Holman pathway, who has talked to other residents going through it at other institutions, and directly interacted with faculty who completed it I'd say, "in the short term it may detract from your clinical competency, but in the end you will be as competent." My reasons for this are (a) you have to be
above average as deemed by your PD and Chair to enter the Holman pathway in the first place and (b) people who do Holman tend to be aggressively "beef up" their clinical knowledge base in the last year or so of residency.
I noted a requirement for 21 months of research time... Is there a requirement for the number of publications that should be generated during this time?
First off the research time can be as short as 18 months and still qualify for Holman. Second, when you apply to the Holman pathway you are simply asking the ABR to allow you to remain board eligible in Radiation Oncology with abbreviated clinical training for the purposes of meritorious research. That's it, nothing more and nothing less. The ABR relies heavily on your PD, Chair and mentor to ensure that you are qualifed to do Holman and only vetoes your application in unusual circumstances. There are no requirements once you are in the Holman pathway other than submitting annual progress reports to the ABR.