Multi-Disciplinary Team Approach (MDT) to Colorectal Cancer
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21 March 2010
The current management of loco-regional colorectal cancer has come to involve a combination of treatment modalities, making multidisciplinary teamwork and coordination essential. The value of pre-treatment consensus and planning cannot be over-emphasized. Furthermore, such multidisciplinary teams (MDT) must continually strive to remain competitive and updated, conscientiously auditing the quality of their care, while regularly evaluating and reporting treatment outcomes.
In resectable colon cancer, protocols are more simple and straight-forward. Surgical resection is often followed by adjuvant chemotherapy. Laparoscopic colon surgery has been proven internationally to be as safe and effective as the open oncologic operations, with better outcomes in terms of pain, cosmesis, earlier discharge and return to work. However, these procedures are expensive and require a steep learning curve. At present, no Filipino surgeon has achieved the necessary experience of at least 30 laparoscopic colon cancer cases to be labeled an expert.
Unresectable, or Stage IV colon cancer, requires a more individualized approach to patients. In a very small minority, cure can still be achieved after aggressive surgical resection of both the primary and metastatic tumors, as well as varied modalities of chemotherapy. Radiofrequency ablation, and to a lesser extent palliative radiotherapy, are available adjuncts in some unresectable cases, although these remain principally investigational in our setting. For incurable obstructing colon lesions, stenting has become an important alternative to emergent surgery and stoma creation, allowing palliative chemotherapy to proceed without the morbidities associated with such surgical procedures. The variety in which such patients present, as well as the necessity for individualizing treatment, further high-lights the need for a multidisciplinary team approach in these settings.
In rectal cancer, patients are burdened, not just with issues of survival, but also with deep-seated concerns about stomas, and sexual/urinary dysfunction. Unlike colon cancer, management is more varied. There are multiple modalities to choose from, making multidisciplinary teamwork, as well as full patient disclosure as to risks and benefits, exceedingly important. In such instances, patient consent is critical.
The treatment for rectal cancer is highly dependent on stage. It is imperative therefore that stage is determined prior to planning out treatment strategies. In our setting, the basic diagnostic modalities for staging will include a chest x-ray, CT scan of the abdomen, colonoscopy, rigid proctosigmoidoscopy, digital evaluation of palpable lesions, and endorectal ultrasound.
A chest x-ray will show if there are distant pulmonary metastasis, as well as determine if other pulmonary co-morbidities exist. CT scan of the abdomen is the most accurate means of detecting liver metastasis. It also gives us an idea of the size of the primary rectal tumor, and its relationship to adjacent structures. Colonoscopy may detect the presence of synchronous tumors (which may be present in 9% of cases), as well as the potential for obstruction of the primary tumor. If the scope cannot be passed through, then obstruction is impending. Rigid proctosigmoidoscopy is the most accurate method of measuring distal tumor distance from the anal verge, while digital evaluation of the tumor allows us to assess whether the tumor involves the anal sphincters, is fixed or mobile, or if there are any palpable nodes. Endorectal and endoanal ultrasonography are the most accurate means of determining T and N status, as well as the integrity of the sphincter complex, although these tests are highly operator-dependent. A stenotic lesion may prevent insertion of the probe, but our experience shows that such stenotic lesions have an 80% probability of being T3N1 or greater.
Once the stage of disease has been determined, then treatment planning can proceed with more focus. Carefully selected T1N0M0 lesions, particularly those that are well-differentiated, <3 cm in diameter, and occupying < 40 % of the circumference, are amenable to curative local transanal excision. Even so, such cases may still have a 12 percent incidence of lymph node metastasis. High risk T1N0M0 lesions, andT2N0M0 lesions (where the incidence of lymph node metastasis may be as high as 22 percent) require radical resection.
Radical resection for mid and low rectal cancers must be done with Total Mesorectal Excision, which achieves local recurrence rates below 10%. TME is defined as the complete excision of visceral mesorectal tissue up to the level of the levators. By mesorectum we mean here the visceral mesentery of the rectum containing lymphovascular structures, which, together with the rectum, forms a circumferential package of tissue that can be excised intact. However, TME does not only involve anatomic and technical issues pertaining just to surgery. The concept of TME is a paradigmatic approach to rectal cancer that includes the six following principles:
- Perimesorectal “Holy Plane” sharp dissection
- Specimen-oriented surgery
- Pathological audit for Circumferential Resection Margins (CRM) and completeness of the specimen as the principal outcome measures of surgery, making the pathologist a very important component of the multidisciplinary team.
- Recognition and preservation of the autonomic nerves and plexi
- Incease in anal preservation and a reduction in the number of permanent colostomies
- Low pelvic reconstruction
A 1 to 2 cm margin is required before contemplating sphincter preservation, but in expert hands this may be possible even for carefully selected lesions as low as 4 cm from the anal verge. Upper rectal lesions require Wide Mesorectal Excision (WME) of at least 5 cm from the distal tumor margin.
Unfortunately, TME is still not routinely practiced in the Philippines. If we are to follow the European model, wide-spread acceptance will require (amongst our surgeons) a change in paradigms, as well as a comprehensive national training program that could involve re-certification and credentialing. Much work still has to be done in this direction.
Aside from radical resection, stage II and III rectal cancers require chemoradiation as well. In our hospital, it is our policy to give radiotherapy pre-operatively in order to down-stage the disease and increase the chances for sphincter preservation. Furthermore, we try to avoid irradiating the pelvises of patients after complex operative procedures to re-establish coloanal integrity and function.
We prefer the more convenient and economical short-course radiotherapy (2,500 cGy X 5 days) for patients with rectal lesions that are amenable to TME and sphincter preservation, with a reasonably good chance of achieving clear circumferential margins. For T4 lesions, or bulky tumors where the circumferential margins appear compromised, or for low rectal tumors where sphincter sacrifice appears necessary, we prefer to give long course chemoradiation (4500 cGy over 5 weeks). The intent is to down-stage the disease, hopefully achieving clear resection margins, as well as increasing the chances for sphincter preservation.
In summary, the treatment of colorectal cancer now calls for a multidisciplinary team approach that integrates the best modalities for individual patients. Management begins with accurate pre-treatment staging, and offers a wide spectrum of options that are highly dependent on stage at diagnosis. In rectal cancer, these strategies have significantly decreased the rates of local recurrence and permanent colostomies. Gone are the days when the decision to perform outright abdominoperineal excision was based solely on the fact that the rectal cancer was within reach of the examining finger.
References:
National Comprehensive Cancer Network Clinical Practice Guidelines in Colon Cancer, 2005.
Tjandra J, Wilkenny JW, Buie D, et al. Practice Parameters for the Management of Rectal Cancer. DCR 2005; 48:411-423.
Crisostomo AC, , Roxas MFT, Chang R, et al. Evidence-Based Clinical Practice Guidelines on the Management of Curable Rectal Cancer. Approved by the PCS Board of Regents, January 2005. For publication.
