(concurring in part and dissenting in part, with whom Lynch, J., joins). I agree that the judgment of dismissal with respect to Dr. Austin ought to be affirmed. *210However, I do not agree that the judgment of dismissal, the order for a bond, and the decision of the medical malpractice tribunal should be vacated as to Dr. Martin and Baystate Medical Center. Under a directed verdict standard, the plaintiffs offer of proof before the tribunal was insufficient to raise a legitimate question either as to whether Dr. Martin’s conduct failed to conform to acceptable medical practice or as to whether any fault on his part caused the patient’s injury and death.
No evidence was offered that would show that Dr. Martin failed to adhere to the “standard of care and skill of the average member of the profession practising the specialty” of vascular surgery. Brune v. Belinkoff, 354 Mass. 102, 109 (1968). The offer of proof consisted almost entirely of hospital records and two letters, which were based on those records, written by Dr. David M. Saltzberg, a gastroenterologist and assistant professor of medicine at University of Maryland Hospital. As a practical matter, whether the plaintiff’s offer of proof was sufficient depends on the content of the letters written by Dr. Saltzberg, the plaintiff’s expert.
The first letter, dated January 16, 1987, stated in relevant part the following. On July 3, 1986, a sonogram of Earl Bradford’s (patient) abdomen was obtained. “This confirmed the presence of the abdominal aortic aneurysm which was noted to be 6.3 cm by 5.8 cm by 5.7 cm, which is rather large. ... A CT scan was obtained on July 5, 1986, to rule out the possibility of abdominal abscess. The CT scan report describes an aneurysm that had expanded to 9 cm in diameter and which may be leaking as evidenced by increased fluid density tracking around the left kidney. The Radiologist describes the aneurysm to be unmistakably enlarging compared to the sonogram of July 3, 1986. However, there is some confusion as to the accuracy of this report as it was dictated after the patient’s demise. To confuse the issue further, a vascular surgeon [Dr. Martin] who saw the patient on the same day of the CT scan, (July 5, 1986) claims that the CT scan shows no evidence of leak and that the patient had no *211back or abdominal pain.1 He suggested elective resection of the aneurysm after the patient’s other problems had been sorted out. He also wanted to see previous abdominal x-rays to decide whether the aneurysm was enlarging. It’s not clear whether the surgeon actually knew of the sonographic and/or CT scan report, or if the radiologist failed to contact the surgeon.”
Dr. Saltzberg’s January 16, 1987, letter continues, noting among other things that the patient suffered cardiac arrest at 12:30 a.m., July 6, and died the same day at 2:00 p.m. Dr. Saltzberg observed that “[s]everal questions are raised by this case,” and, in answer to the first question he concluded that “the rupture of aorta was clearly due to Salmonella infection.” He answered a second question by stating his belief that the initial treatment of the patient was appropriate. “The third and fourth questions,” he said, “relate to [the patient’s] terminal admission. Was he appropriately managed? Could his life have been saved? I think in retrospect his symptoms necessitating admission were related to expansion of the aneurysm. By the 3rd of July, the physicians knew he had a rather large aneurysm with Salmonella still in his system along with low grade fevers. These signs should have raised the question of an infected aneurysm but did not necessarily warrant emergency surgery. The interpretation of the CT scan, however, which was obtained on [July] 5th is crucial to understanding his management. At the very least there was a lot of confusion. The CT scan report dictated following the patient’s demise described a rapidly enlarging and leaking aneurysm. On the other hand, the vascular surgeon claims there was no evidence of leak. Did the radiologist initially misread the film and mislead the surgeon (and then after the patient’s death amend the report)? Or, did the surgeon actually not speak with the radiologist or did he not closely scrutinize the CT scan? I’m not sure which is true, *212but if the aneurysm was clearly identified as rapidly expanding, the patient should have had emergency surgery that evening, or at the very least be considered for the next morning. Neither of these options was considered. . . . Clearly the patient’s management was not appropriate and the hospital has some responsibility for this whether it be due to poor judgment from the radiologist or the surgeon. Once the patient arrested, his probability for survival was minimal. . . .
“Could this patient have been saved? [The patient] had a mycotic aneurysm, which has a high mortality rate, estimated to be 50-60%. This was unknown pre-operatively. Thus, the patient may very well have died even if he had surgery that evening prior to the rupture. His only chance would have been for emergency surgery at the latest on July 5, 1986, but preferably after the sonogram on July 3, 1986. His physicians did not provide him with that opportunity due [to] their misjudgment and/or lack of attention to the critical details of [the patient’s] case. Standard practice in the community dictated urgent surgical intervention for rapidly expanding aneurysm regardless of etiology. There was therefore, in my professional opinion significant errors in judgment likely constituting medical malpractice.”
Dr. Saltzberg wrote a second letter, dated August 14, 1990, which was part of the plaintiffs offer of proof before the tribunal. I shall refer to the portions of that letter that are of particular significance to the case against Dr. Martin. The letter mentions the ultrasound (i.e., sonogram) performed on July 3, 1986, and its disclosure of “a large aortic aneurysm of 6.3 x 5.8 x 5.7 cm.” The letter states, “Although an aneurysm of this size should be repaired surgically it is not necessary to do emergency surgery unless it is believed that the aneurysm is leaking or rapidly expanding.” The August 14, 1990, letter also states: “An abdominal CAT scan was performed on July 5. A large aneurysm that was 8 x 9 cm was identified on the CAT scan. Dr. Kevin Martin of Vascular Surgery evaluated the patient on the late afternoon of [July] 5th. He reviewed the CAT scan and noted the aneurysm but stated in a note that there was no *213evidence of leakage. He considered the possibility of an enlarging aneurysm but felt that the lack of pain by the patient and the absence of leakage on the CAT scan made it unlikely that the aneurysm was expanding, although the patient had persistently complained of back pain [see note 1, supra; Dr. Martin noted no back pain consistent with leaking of the aneurysm]. He did attempt to retrieve earlier x-rays to see if he could determine how quickly the aneurysm might be growing and indicated that the aneurysm did need to be repaired, but that this could be done electively.
“During the early morning hours of July 6, the aneurysm ruptured. The patient was immediately taken to the Operating Room and was found to have a grossly purulent aorta. At this point there was really nothing that could be done to save the patient, and he expired later in the day. The official abdominal CAT scan report dictated on July 6 indicated that the patient had an expanding leaking aortic aneurysm.”2
Dr. Saltzberg’s second letter further stated: “It is apparent that there were problems with the medical care received by [the patient] on July 5. Dr. Martin quotes the aneurysm as *214being 9x8 cm, which is much larger than that seen on the ultrasound of two days earlier. He further stated that there was no evidence of leakage from the aneurysm. Yet, the final CAT scan report indicated that there was a large expanding leaking aneurysm [see note 2, supra]. Dr. Austin, who interpreted the ultrasound two days previously, was the radiologist who read the abdominal CAT scan. If an expanding or leaking aneurysm had been documented, the patient should have been scheduled for surgery that evening. If the patient had been taken immediately to the Operating Room, he might have survived. By waiting until the aorta ruptured to operate, any chance for survival was removed. . . . Clearly, on the 5th of July there was confusion and/or misunderstanding as to the pertinent medical facts, which may have contributed to [the patient’s] demise by delaying surgery. Did Dr. Austin misinterpret the CAT scan on July 5 and give Dr. Martin misinformation only to correct his reading on July 6? Did Dr. Martin actually review the CAT scan in depth with Dr. Austin? Why was the CAT scan not compared to the ultrasound of July 3? Was Dr. Martin aware of the July 3 ultrasound and, if so, why did he delay therapy for an expanding aneurysm?”
The expert’s letters ask many questions. The letters supply very few answers. For example, there is no evidence that, had he exercised the care and skill of an average vascular surgeon in all the circumstances present between late afternoon on July 5, and the rupture of the aneurysm, Dr. Martin would have known prior to the rupture that the aneurysm was rapidly expanding. Also, although Dr. Austin’s report concerning the July 5 CT scan described an aneurysm that had expanded and could , have been leaking, the report was dictated long after the rupture had occurred. There is no evidence that Dr. Austin was accessible to Dr. Martin between the late afternoon of July 5 and the aneurysm’s rupture, and there is no evidence that, in concluding that the CT scan failed to reveal evidence that the aneurysm was leaking, Dr. Martin failed to meet the standard of care and skill of the average vascular surgeon. Brune v. Belinkoff, 354 Mass. 102, *215109 (1968). Likewise, there is no evidence either that Dr. Martin was wrong when he concluded that the patient had no back pain consistent with an abdominal aortic aneurysm leak, or that, if he was wrong as to that, Dr. Martin failed to meet the requisite standard of care and skill in reaching that conclusion.
The expert’s letters do not even allude to the standard of care and skill of the average vascular surgeon. The letters demonstrate no attempt to measure Dr. Martin’s conduct by such a standard, and surely, apart from those letters, nothing in the record, under a directed verdict standard, shows negligence (malpractice) on the part of Dr. Martin. The court states, ante at n.6, that “[t]he gastroenterologist stated [in his letter dated August 14, 1990] that ‘[i]f an expanding or leaking aneurysm had been documented, the patient should have been scheduled for surgery [the] evening [of July 5].’ This is an opinion on the course of action that one reasonably exercising the care and skill of an average vascular surgeon should have followed.” As the hospital record indicates and Dr. Saltzberg’s letter dated January 16, 1987, confirms, the final report relative to the CAT scan done on July 5, 1986, was not even dictated by Dr. Austin, the radiologist, until after the patient’s demise and, as I have stated in note 2, supra, the report when dictated did not say that there was an expanding, leaking aneurysm. Most importantly, there is no expert opinion in the record that an expanding or leaking aneurysm should have been documented before it was documented, or that Dr. Martin, rather that Dr. Austin, the radiologist, should have documented it and then scheduled the patient for surgery on the evening of July 5. The gastroenter-ologist’s observation that, if an expanding or leaking aneurysm had been documented sooner, the patient should have been scheduled for surgery, does not come close to constituting an expert’s opinion that “one reasonably exercising the care and skill of an average vascular surgeon” would have done anything that, according to the record, Dr. Martin failed to do, or would have refrained from doing anything that Dr. Martin did. For that reason alone, the claim against *216Dr. Martin, as well as the claim against Baystate Medical Center based on Dr. Martin’s negligence, were properly dismissed. The plaintiff does not argue that, even if she failed to raise a legitimate question of liability as to Drs. Austin and Martin, which, in my view, she failed to do, she nevertheless succeeded in raising such a question with respect to Baystate.
I would affirm the judgment below solely on the ground that no legitimate question of malpractice was demonstrated before the medical malpractice tribunal. I speak briefly, however, to the causation question. The court observes that “[t]he traditional rule of tort law is that a plaintiff must show that it is more probable than not that the injury was caused by the defendant’s negligence. See Forlano v. Hughes, 393 Mass. 502, 507-508 (1984). If one were to apply that rule strictly in this case, the plaintiff’s evidence has not passed the test.” Ante at 208. The court then goes on to say, ante at 208, that “there is reason to question [such] a rule of law” in a case like the present one and that, until the court resolves the question, medical malpractice tribunals should conclude as to the causation factor that a legitimate question of liability has been shown where there is evidence that a defendant’s malpractice resulted in the patient’s “loss of a substantial chance to survive.” Ante at 209. If such a rule were to be adopted, the causation necessary to liability might be shown by an offer of proof that leaves to speculation the question whether the asserted malpractice probably resulted in the injury or death complained of, and indeed might be shown by an offer of proof that affirmatively demonstrates, as it does in this case, that the injury or death probably would have occurred without malpractice. It is my view that, unless and until such a radical departure from traditional tort law is adopted in this Commonwealth, a course that should not be followed, the responsibility of a medical malpractice tribunal is to determine whether the plaintiff’s offer of proof, if substantiated, is “sufficient [in the light of current tort law] to raise a legitimate question of liability appropriate for judicial inquiry.” G. L. c. 231, § 60B (1990 ed.). In this case, if there had been evidence of *217negligence, a determination by the tribunal that a legitimate question of liability had been raised despite lack of proof of probable causation would have violated the tribunal’s statutory mandate. Therefore, I would affirm the judgment below because the plaintiffs offer of proof to the tribunal was insufficient both as to negligence and causation. The bond was properly ordered, and the dismissal of the case in response to the plaintiffs failure to file a bond was correct.
Dr. Martin’s entry in the patient’s hospital progress notes says in relevant part, “No back pain/flank pain that would be C/W [consistent with] AAA [abdominal aortic aneurysm] expansion leak & no evidence of leak on CT.”
The final CT scan report does not indicate that there was a large expanding leaking aneurysm. Dr. Austin’s report in relevant part is as follows:
“1. Given the large size of the aorta, the possibilities include leaking along the renal pedicle into the perinephric space with the collection around the kidney representing chronically accumulating blood. The other possibility includes leaking of the aorta or perhaps compression by the aorta accounting for dilatation of the left collecting system with a density around the kidney being related to extravasated urine.
“2. Large aortic aneurysm with changes as described above. Clearly leak of the aneurysm must be considered particularly in light of changes around the left kidney and increase in size since the prior ultrasound examination as well as position of intimal calcification.” (Emphasis added.)
The following addendum, entered July 14, 1986, appears at the end of the report:
“ADDENDUM: This addendum is to say that the C.T. report was dictated on the day following the C.T. Scan at which point the paperwork necessary for the dictation was available. The report was dictated following and with the knowledge of the patient’s course over the hours subsequent to the C.T. Scan.
“/s/ Robert Austin M.D.”