I am a junior faculty member at a top 5-10 program and am involved with both our residency and very closely with the affiliated med school, so I have some insights into how rad onc is faring compared to other fields in terms of anxieties and existential crises, which have been really abounding on this forum over the past 1-2 years. Take what I say with a grain of salt though, since both the med school and our residency are relatively well-reputed so your mileage may vary coming from other backgrounds/residencies.
I think a lot of the angst on this forum is legitimate and I don't want to minimize anyone's troubles finding a job or anxieties about being able to find a job. However, I think a lot of this is overblown and a little bit of "grass is greener" mentality.
1. You can still make a ton of money in rad onc compared to most other fields which have similar hours. Most clinic-based specialties do not allow you to easily make a starting $300K working 32-40 hours per week. Yes, dermatologists make that much, but most 9-5 jobs in medicine are not like that. When you have kids, you will realize how important this schedule is, including no call or real weekend responsibilities. Yes hospitalists can make the same amount for the same amount of "in-house" time, but they work every other weekend for their entire lives and have random weekdays off. This is useless when it comes to spending time with your family and is really only amenable to a 20s/early 30s lifestyle. Yes, the job market is not as good as it was 15 years ago, meaning you can't make 500-600K (in 2018 dollars) working 4 days a week wherever in the country you want. The geographic limitation is the only downside of rad onc, but if you are flexible (move somewhere less than ideal after residency) and hustle (keep in touch with practices in your desired area) you are likely to eventually be able to move there. 3 years in Kansas (making half a million per year) is a small price to pay for the major lifestyle and career satisfaction benefits of rad onc, especially compared to what many other fields go through (e.g. 6 years of hell to become a cardiologist). I hope the job market gets back to mid 2000s level, which it might given retiring baby boomers and growing indications for radiation (see #2 below) but even if radiation oncologists have to split the current pie, the salary (especially per hour of actual work) will still be very high among medical specialties.
2. Indications/duration of radiation is changing (e.g. hypofrac) but growing in other areas. This is most relevant this week with the recent ESMO (edit: meant ASTRO, but looks like this applies to ESMO now too) data. Yes, you will now be paid ~70% for a breast course as you were 15 years ago. Maybe the same thing will happen to prostate. That sucks financially for our field. But there are major areas of rad onc that are growing and already are making some rad oncs very rich that the doom and gloom on this board do not ever mention. Lung cancer screening and lung cancer SBRT could generate as much or more money as all the prostates in the country. Prostate SBRT (if it actually works), while being paid less than a 44 fraction course, may double RO volume if patients no longer want prostatectomies given they could finish their prostate SBRT before they even come for the first post-op visit with the urologist. And the biggest elephant in the room is SBRT for oligometastatic disease or oligoprogression, especially on immunotherapy. This is a massive trove of patients who we never cared for. In residency, if I saw that a patient in multi clinic had metastatic disease, my eyes would basically glaze over and I would just see if anything was acutely symptomatic, and if not, would quickly exit the appointment. In 2018 with immunotherapy and promising data on oligometastatic SBRT (which many of us have long-believed in anyway), there may be an explosion of well-reimbursed SBRT in the coming years which could end up making more than 50% of a typical attending's volume. Couple this with the fact that SBRT is becoming easier and more efficient to deliver with stable reimbursement, this bodes well for our compensation. This is what our thoracic attendings have experienced over the past 10 years, where SBRT used to be a big to-do requiring significant physician time, and now is as routine as anything else we treat.
3. Other fields have existential/job market concerns as well. Yes, radiation may not be around forever. There is always the threat that the next big systemic therapy may make radiation obsolete or diminish it's role. But this concern is there in many fields. Here are some of the anxieties I have heard from the med students I advise for "lifestyle"/competitive specialties, starting with the classic "ROAD." I am painting with a broad brush here but this is just to illustrate every field has anxieties. Overall, despite these anxieties I am confident the smart men and women in each of these fields will adapt their fields and keep them relevant.
Radiology--AI may make this obsolete, plenty about this on the radiology forums
Ophthalmology--A good field, but ultimately based entirely on extremely quick visits which may be susceptible to other practitioners (e.g. optometrists) taking a lot of the volume. Right now regulations prevent this type of encroachment, but it is certainly possible that optometrists could become like CRNAs for anesthesia and work under the supervision of an ophthalmologist, including even cataract surgery which ultimately is learned in 1 year of most ophtho residencies. That would be great financially for the one ophtho supervising 5 optometrists, but not so great for the 5 ophtho's now out of work.
Anesthesia--CRNA's taking over. Plenty about this on the anesthesia forums
Dermatology--okay this one will always be lucrative and protected.
Now some of the other competitive fields
Emergency Medicine--will never be obsolete, but there is reason these guys retire young. Even though they make good money working 32-40 hours per week, having 8-16 of those hours be overnight or otherwise odd hours wears on you, again most significant when you have kids.
Med Onc--Our closest parallel. Will obviously never be obsolete, but what we forget is that these guys are working hard and fast, seeing a lot more patients, quick visits, and generally really churning, and at least in 2018, I doubt any med onc is being paid more for all of this extra work compared to the rad onc sitting right next to him in tumor board who gets 1 hour per new consult. This is an unfortunate reality of how American medicine is paid for, which is that people who "treat" (radiation, procedures, even infusions to an extent) will always make more than people who assess/diagnose and simply prescribe a medication.
Any surgical subspecialty (ENT, uro, NSGY, etc)--Reimbursement cuts. Yes, all fields may have declining reimbursements. But in the "worst case" when all physicians are paid almost the same (like they are in many European countries), the neurosurgeon who slaved away 90 hours a week for 5 years as a resident and then 60 hours a week as an attending will be a lot more upset making $250K/year than the radiation oncologist who worked 55 hours a week as a resident and 40 hours as an attending making $225K/year.
IM subspecialties (GI, cards)--Like surgeons, these guys work HARD. They are also completely dependent on one or two major procedures. For GI, CT colonography or another (e.g. stool genetics) screen for colon cancer could really damage their financial future. For cardiology, echo and cath reimbursements have been declining, and despite all of the valuable good work they do, unfortunately a lot of their pay does come from these "procedures" so my classmates who are cardiologists complain about reimbursement cuts even more than rad oncs.
All of this is to say that yes radiation oncology is not perfect and there are issues, both job market related and big-picture/existential. But there are a lot of positives to our field that this board neglects to mention, and placing our field side-by-side with other competitive fields highlights that you can always find something to worry about no matter what field you are in. I think this negative attitude does med students a disservice since they will wrongly assume these anxieties are limited to radiation oncology, when really these concerns are present in nearly every competitive field. Ultimately I think the way med students should choose a field is based on the classic advice of choosing what you love clinically, and not worrying too much about the other stuff, since the specifics of job markets, reimbursement, etc can change even every few years.