In a large multi-regional cohort of surgeons treating patients with colorectal cancer, colorectal surgeons and surgical oncologists were more likely than general surgeons to perform a high volume of colorectal cancer resections, as were surgeons who practiced at NCI-designated cancer centers and those who attended weekly tumor board meetings (although these latter two findings were of borderline statistical significance). We found important differences between higher- and lower-volume surgeons in their tendency to collaborate when making decisions about possible use of adjuvant therapy. Controlling for physician and practice characteristics, higher-volume surgeons were more likely than lower-volume surgeons to report collaborative patterns of care regarding decision making about adjuvant chemotherapy and radiation therapy. Although we cannot demonstrate causal relationships, such collaboration may contribute to the greater likelihood that patients of high-volume surgeons receive appropriate adjuvant therapies.18
This collaboration may thus be a partial mediator of greater adherence to evidence-based guidelines for adjuvant therapies observed among patients of high-volume providers of colorectal cancer care.
Prior studies suggest greater collaboration of care may help to improve the quality of colorectal cancer care delivered. Referral to a medical oncologist has been identified as one of the key factors associated with receipt of chemotherapy,15, 17
which has been reported as limited in many individuals with stage III colon cancer, particularly older patients.9, 14, 15
Because surgeons play a major role in referring patients to medical oncologists and radiation oncologists, patients of surgeons who collaborate more with these specialists may be more likely to be referred to medical oncologists and radiation oncologists and receive indicated adjuvant therapies. One study found that many physicians held views opposite to guidelines recommending adjuvant chemotherapy and radiation therapy for stage II and III rectal cancer.23
Greater collaboration of surgeons with medical oncologists and radiation oncologists may increase sharing of knowledge about evidence-based guidelines and help to prevent underuse of recommended adjuvant therapies.
Although high procedure volume may be associated with better operative technique, it may also serve as a proxy for the performance of other recommended processes of care.7
One study found that worse colon cancer outcomes in low-volume hospitals were not explained by cancer recurrence11
and suggested that it may be related to worse care of comorbid conditions (which may also rely heavily on collaboration), leading authors to advocate for a greater focus on multidisciplinary aspects of hospital care for improving patient outcomes.12
On the other hand, because rectal cancer surgery may be more technically challenging, surgical volume may still be important for optimizing rectal cancer outcomes related to intraoperative techniques, particularly the likelihood of permanent colostomy8, 16
and the use of total mesorectal excision to prevent local recurrences.
In this study, colorectal surgeons and surgical oncologists tended to perform a higher-volume of colorectal resections than general surgeons. Even after controlling for surgical volume, they were more likely to report collaborating with other physicians regarding decisions about adjuvant therapy. Because their practice is more focused on colorectal cancer patients, they may have stronger relationships with medical and radiation oncologists, making collaborative decisions more feasible. Surgeons who perform many colorectal cancer resections are more focused on colorectal cancer and may thus be more able to form collaborative relationships with other providers who care for these patients.
Not all colorectal cancer patients will go to a high colorectal cancer volume center and neither will they all go to a colorectal or cancer specialty surgeon. For these patients, systems of care that facilitate collaborative interactions may be needed. For example, tumor boards could provide this structure for the co-management of colorectal cancer patients. Systems to facilitate regular attendance at tumor board meetings may increase opportunities for surgeons to have collaborative interactions with medical and radiation oncologists, which may increase the likelihood of recommending appropriate adjuvant therapies. In one study, presentation of a patient's case at a tumor board predicted receipt of recommended therapy for rectal cancer.14
Multidisciplinary collaboration may be challenging for surgeons in rural settings or solo practices, as there may be few medical oncologists and radiation oncologists with whom to collaborate. Telemedicine services may be one option to provide for just-in-time consultations with medical oncologists to facilitate co-management options for surgeons who do not have opportunities for regular interactions with other cancer specialists.
Strengths of our study included a large cohort of surgeons who performed colorectal cancer resection practicing in diverse geographic areas and health-care organizations and our response rate among surgeons of 62.5%.24
However, the study had several limitations. First, surgeons’ self-reported their approach to decision-making about adjuvant therapies, and their responses may be subject to recall bias or social desirability bias. Second, surgeons may have incorrectly self-reported their surgical volume, although this would likely result in random error rather than a systematic bias. Third, our cross-sectional data allow us to observe associations but cannot determine causal relationships between surgical volume and collaborative decision-making about adjuvant therapies. It is possible that surgeons who collaborate frequently have higher-volume practices than others because their collaborators refer patients to them. Fourth, although we demonstrate more collaborative care among high-volume surgeons, we are not able to demonstrate that this is the mechanism for higher rates of adjuvant therapy (or improved outcomes) among patients of high-volume surgeons. Future research will be important to examining these relationships further. Finally, because our sample was not a national sample and the survey is subject to non-response bias, we cannot be certain that the surgeons in our sample were representative of surgeons caring for cancer patients nationally or in the regions studied.
In conclusion, the active collaboration by surgeons in decisions about adjuvant therapies may be a potential mechanism for the better outcomes observed in other studies for patients with colorectal cancer treated by high-volume surgeons.7-10, 12, 16
Additional research is needed to confirm whether better collaboration between surgeons and other providers about adjuvant chemotherapy and radiation for patients with colorectal cancer leads to better outcomes. Such research will help to disentangle the relative contributions of hospital and surgical volume, structure, and processes of care to explain these outcome differences.