Preoperative chemoradiotherapy with oral doxifluridine plus low-dose oral leucovorin in unresectable primary rectal cancer

Stereotactic MR-guided adaptive radiotherapy (SMART) for primary rectal cancer: evaluation of early toxicity and pathological response

Background

The purpose of this study is to measure the effects of stereotactic MR-guided adaptive radiotherapy (SMART) for rectal cancer patients in terms of early toxicity and pathological response.

Materials and methods

For this prospective pilot study, patients diagnosed with locally advanced rectal cancer (LARC) with positive lymph node clinical staging underwent SMART on rectal lesion and mesorectum using hybrid MR-Linac (MRIdian ViewRay). Dose prescription at 80% isodose for the rectal lesion and mesorectum was 40 Gy (8 Gy/fr) and 25 Gy (5 Gy/fr), respectively, delivered on 5 days (3 fr/week). Response assessment by MRI was performed 3 weeks after SMART, then patients fit for surgery underwent total mesorectal excision. Primary endpoint was evaluation of adverse effect of radiotherapy. Secondary endpoint was pathological complete response rate. Early toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE v5.0).

Results

From October 2020 to January 2022, twenty patients underwent rectal SMART. No grade 3-5 toxicity was recorded. Twelve patients were eligible for total mesorectal excision (TME). Mean interval between the completion of SMART and surgery was 4 weeks. Pathological downstaging occurred in all patients; rate of pathological complete response (pCR) was 17%. pCR occurred with a prolonged time to surgery (> 7 weeks).

Conclusion

To our knowledge, this is the first study to use stereotactic radiotherapy for primary rectal cancer. SMART for rectal cancer is well tolerated and effective in terms of tumor regression, especially if followed by delayed surgery.

Evaluation and Predictive Factors of Complete Response in Rectal Cancer after Neoadjuvant Chemoradiation Therapy

The response to neoadjuvant chemoradiation therapy is an important prognostic factor for locally advanced rectal cancer. Although the majority of the patients after neoadjuvant therapy are referred to following surgery, the clinical data show that complete clinical or pathological response is found in a significant proportion of the patients. Diagnostic accuracy of confirming the complete response has a crucial role in further management of a rectal cancer patient. As the rate of clinical complete response, unfortunately, is not always consistent with pathological complete response, accurate diagnostic parameters and predictive markers of tumor response may help to guide more personalized treatment strategies and identify potential candidates for nonoperative management more safely. The management of complete response demands interdisciplinary collaboration including oncologists, radiotherapists, radiologists, pathologists, endoscopists and surgeons, because the absence of a multidisciplinary approach may compromise the oncological outcome. Prediction and improvement of rectal cancer response to neoadjuvant therapy is still an active and challenging field of further research. This literature review is summarizing the main, currently known clinical information about the complete response that could be useful in case if encountering such condition in rectal cancer patients after neoadjuvant chemoradiation therapy, using as a source PubMed publications from 2010–2021 matching the search terms “rectal cancer”, “neoadjuvant therapy” and “response”.

Adaptive radiation dose escalation in rectal adenocarcinoma: a review

Total mesorectal excision (TME) after neoadjuvant chemoradiotherapy (CRT) has offered superior control for patients with locally advanced rectal cancer, but can carry a quality of life cost. Fortunately, some patients achieve a complete response after CRT alone without the added morbidity caused by surgery. Efforts to increase fidelity of radiation treatment planning and delivery may allow for escalated doses of radiotherapy (RT) with limited off-target toxicity and elicit more pathological complete responses (pCR) to CRT thereby sparing more rectal cancer patients from surgery. In this review, methods of delivering escalated RT boost above 45-50.4 Gy are discussed including: 3D conformal, intensity-modulated radiotherapy (IMRT), and brachytherapy. Newly developed adaptive boost strategies and imaging modalities used in RT planning and response evaluation such as magnetic resonance imaging (MRI) and positron emission tomography (PET) are also discussed.

Chemotherapy Alone for Patients With Stage II/III Rectal Cancer Undergoing Radical Surgery

PURPOSE

The purpose of this prospective pilot study was to determine the efficacy of preoperative chemotherapy with six cycles of FOLFOX 6 (without radiation therapy) followed by radical surgery followed by six additional cycles of FOLFOX 6 for patients with stage II/III rectal cancer.

PATIENTS AND METHODS

From January 2010 to January 2014, patients with locally advanced rectal cancer who met the eligibility criteria were enrolled in this study. Patients received FOLFOX 6 chemotherapy comprising oxaliplatin and leucovorin calcium i.v. over 2 hours on day 1, then bolus, and then continuous fluorouracil i.v. over 46 hours on days 1 and 2. Treatment was repeated every 14 days for 6 courses followed by radical surgery followed by additional 6 cycles of FOLFOX 6.

RESULTS

In total, 45 patients were enrolled in this study. In the preoperative re-evaluation, the overall response rate was 68.8% (clinical complete response was 4.4%, and the partial response was 64.4%). There were 14 cases (31.2%) of stable disease. No patients had progressive disease. Postoperatively, the pathologic complete response rate was 8 of 45 (17.8%; 95% confidence interval [CI]: 8.9%-28.9%). The median follow-up was 29 months (range 9-54 months). The actuarial 3-year overall survival and disease-free survival rates for all patients were 80.8% (standard error, 1.877; 95% CI: 69.3%-92.3%) and 67.9% (standard error, 2.319; 95% CI: 54.3%-81.5%), respectively.

CONCLUSION

Neoadjuvant chemotherapy (FOLFOX) without radiotherapy is active and safe but cannot be considered a standard of care until the results of prospective randomized phase III trials are available.

IMPLICATIONS FOR PRACTICE

Neoadjuvant radiotherapy of rectal cancer represents the current standard of care. However, its use is also associated with short-term toxicity and long-term morbidity. With the increasing use of total mesorectal resection resulting in better local control and advances in systemic therapy for colorectal cancer, this study highlights the question of whether radiation is a necessary component of neoadjuvant therapy for all patients with rectal cancer or whether select patients could be spared the additional toxicities and inconvenience of radiotherapy. This study suggests that neoadjuvant FOLFOX without radiotherapy is active and safe, but it could not be considered a standard of care till now.

Future directions for monitoring treatment response in colorectal cancer

Treatment of advanced colon and rectal cancer has significantly evolved with the introduction of neoadjuvant chemoradiation therapy so much that, along with more effective chemotherapy regimens, surgery has been considered unnecessary among some institutions for select patients. The tumor response to these treatments has also improved and ultimately has been shown to have a direct effect on prognosis. Yet, the best way to monitor that response, whether clinically, radiologically, or with laboratory findings, remains controversial. The authors' aim is to briefly review the options available and, more importantly, examine emerging and future options to assist in monitoring treatment response in cases of locally advanced rectal cancer and metastatic colon cancer.

Systematic review and meta-analysis of outcomes following pathological complete response to neoadjuvant chemoradiotherapy for rectal cancer

BACKGROUND

Following neoadjuvant chemoradiotherapy (CRT) and interval proctectomy, 15-20 per cent of patients are found to have a pathological complete response (pCR) to combined multimodal therapy, but controversy persists about whether this yields a survival benefit. This systematic review evaluated current evidence regarding long-term oncological outcomes in patients found to have a pCR to neoadjuvant CRT.

METHODS

Three major databases (PubMed, MEDLINE and the Cochrane Library) were searched. The systematic review included all original articles reporting long-term outcomes in patients with rectal cancer who had a pCR to neoadjuvant CRT, published in English, from January 1950 to March 2011.

RESULTS

A total of 724 studies were identified for screening. After applying inclusion and exclusion criteria, 16 studies involving 3363 patients (1263 with pCR and 2100 without) were included (mean age 60 years, 65·0 per cent men). Some 73·4 per cent had a sphincter-saving procedure. Mean follow-up was 55·5 (range 40-87) months. For patients with a pCR, the weighted mean local recurrence rate was 0·7 (range 0-2·6) per cent. Distant failure was observed in 8·7 per cent. Five-year overall and disease-free survival rates were 90·2 and 87·0 per cent respectively. Compared with non-responders, a pCR was associated with fewer local recurrences (odds ratio (OR) 0·25; P = 0·002) and less frequent distant failure (OR 0·23; P < 0·001), with a greater likelihood of being alive (OR 3·28; P = 0·001) and disease-free (OR 4·33, P < 0·001) at 5 years.

CONCLUSION

A pCR following neoadjuvant CRT is associated with excellent long-term survival, with low rates of local recurrence and distant failure.

Pathologic complete response after neoadjuvant treatment for rectal cancer decreases distant recurrence and could eradicate local recurrence

BACKGROUND

The aim of this study was to evaluate the clinical implications of pathologic complete response (pCR) (i.e., T0N0M0) after neoadjuvant chemoradiation and radical surgery in patients with locally advanced rectal cancer.

MATERIALS AND METHODS

A single-center, prospectively maintained colorectal cancer database was queried for patients with primary cII and cIII rectal cancer staged by CT and ERUS/MRI undergoing long-course neoadjuvant chemoradiation followed by proctectomy with curative intent between 1997 and 2007. Patients were stratified into pCR and no-pCR groups and compared with respect to demographics, tumor and treatment characteristics, and oncologic outcomes. Outcomes evaluated were 5-year overall survival, disease-free survival, disease-specific mortality, local recurrence, and distant recurrence.

RESULTS

The query returned 238 patients (73% male), with a median age of 57 years and median follow-up of 54 months. Of these, 58 patients achieved pCR. Patients with pCR vs no-pCR were statistically comparable with respect to demographics, chemoradiation regimens, tumor distance from anal verge, clinical stage, surgical procedures performed, and follow-up time. No patient with pCR had local recurrence. Overall survival and distant recurrence were also significantly improved for patients achieving pCR.

CONCLUSIONS

Achievement of pCR after neoadjuvant chemoradiation is associated with greatly improved cancer outcomes in locally advanced rectal cancer. Future studies should evaluate the relationship between increases in pCR rates and improvements in cancer outcomes in this population.

Outcomes of clinical T4M0 extra-peritoneal rectal cancer treated with preoperative radiochemotherapy and surgery: a prospective evaluation of a single institutional experience

BACKGROUND

Our objective was evaluate the outcome of primary clinical T4M0 extraperitoneal rectal cancer treated by neoadjuvant radiochemotherapy. Prognosis of clinical T4 rectal cancer is poor. Preoperative chemoradiation therapy may be beneficial. The results obtained are unclear due to lack of objective and strictly applied staging methods.

METHODS

Patients with primary, clinical, T4MO, extraperitoneal rectal cancer, defined by transrectal ultrasonography, computed tomography or magnetic resonance imaging, were considered. Intraoperative radiotherapy and adjuvant chemotherapy were employed in some patients after curative resection (R0). Variables influencing the possibility to perform an R0 resection and a sphincter-saving procedure were investigated as predictors of outcome.

RESULTS

100 patients were included. R0 resection was performed in 78 patients. R0 resection rate was greater in females (93% vs 67%) and in responders to neoadjuvant chemoradiation (94% vs 60%). The ability to perform a sphincter-saving procedure was 57%, greater in middle rectal location (85% vs 51%) and in responders to the chemoradiation (70% vs 47%). Median follow-up was 31 months (range, 4-136). Local recurrences were found in 7 patients (10%). Five-year local control in R0 patients was 90% and better in the IORT group (100%). Distant relapse occurred in 24 patients (30%). Five-year overall survival was 59%, and was better after an R0 versus an R1 or R2 resection (68% vs 22%). Overall and disease free survival in R0 patients improved after overall downstaging. Adjuvant chemotherapy given in addition to the neoadjuvant therapy did not appear to offer benefit in improving survival.

CONCLUSION

A multimodal approach enabled us to obtain a 5-year overall survival of about 60%. IORT increased local control. The role of adjuvant chemotherapy needs to be further investigated.

Chemoradiotherapy for rectal cancer: an updated analysis of factors affecting pathological response

AIMS

With the aim of improving locoregional control, the use of preoperative chemoradiotherapy (CRT) for rectal cancer has increased. A pathological complete response (pCR) is often used as a surrogate marker for the efficacy of different CRT schedules. By analysing factors affecting pCR, this analysis aims to guide the development of future trials.

MATERIALS AND METHODS

Searches of Medline, EMBASE and the electronic American Society of Clinical Oncology abstract databases were carried out to identify prospective phase II and phase III trials using preoperative CRT to treat rectal cancer. Trials were eligible for inclusion if they defined: the CRT drugs, the radiation dose and the pCR rate. Phase I patients were excluded from the analysis. A multivariate analysis examined the effect of the above variables on the pCR rate and in addition the use of neoadjuvant chemotherapy, the type of publication (peer reviewed vs abstract), the year of publication and whether the cancers were stated to be inoperable, fixed or threatening the circumferential resection margin were included. The method of analysis used was weighted linear modelling of the pCR rate.

RESULTS

Sixty-four phase II and seven phase III trials were identified including a total of 4732 patients. Statistically significant factors associated with pCR were the use of two drugs, the method of fluoropyrimidine administration (with continuous intravenous 5-fluorouracil being the most effective) and a higher radiotherapy dose. Although the use of two drugs was associated with a higher rate of pCR, no single schedule seemed to be more effective. None of the other factors analysed significantly influenced pCR.

CONCLUSIONS

A higher rate of pCR is seen in studies using two drugs, infusional 5-fluorouracil and a radiotherapy dose of 45 Gy and above.

Complete clinical response after preoperative chemoradiation in rectal cancer: is a "wait and see" policy justified?

PURPOSE

A proportion of patients, who receive preoperative chemoradiation for locally advanced (T3, T4, NX) rectal cancer achieve a complete clinical response and a pathologic complete response in the region of 15 to 30 percent. Support is growing in the United Kingdom for the concept of "waiting to see" and not proceeding to radical surgery when a complete clinical response is observed. The purpose of this review was to use a literature search to assess how often complete clinical response is achieved after neoadjuvant chemoradiation, the concordance of this finding with pathologic complete response, and to determine whether it is feasible to observe patients who achieve complete clinical response rather than proceed to surgery.

RESULTS

In total, 218 Phase I/II or retrospective studies and 28 Phase III trials of preoperative radiotherapy or chemoradiation were identified: 96 percent of trials documented the pathologic complete response, but only 38 trials presented data on the achievement of a complete clinical response/partial clinical response. Only five studies were found in which patients with clinically staged T2/T3 tumors were treated with radiotherapy/chemoradiation and did not routinely proceed to surgery and also reported on the long-term outcome of a "wait and see" policy.

DISCUSSION

It remains uncertain whether the degree of response to chemoradiation in terms of complete clinical response or pathologic complete response is a useful clinical end point. Studies that include T3 rectal cancer are associated with high local recurrence rates after nonsurgical treatment. Few studies report long-term outcome after achievement of a complete clinical response.

CONCLUSIONS

The end point of complete clinical response is inconsistently defined and seems insufficiently robust with only partial concordance with pathologic complete response. The rationale of a "wait and see" policy when complete clinical response status is achieved relies on retrospective observations, which are currently insufficient to support this policy except in patients who are recognized to be unfit for or refuse radical surgery.

Serum CEA as a predictor for the response to preoperative chemoradiation in rectal cancer

BACKGROUND AND OBJECTIVES

Recent data suggest that good responders to preoperative chemoradiation (CRT) have a favorable prognosis in rectal cancer patients. The aim of this study was to investigate the predictive value of serum carcinoembryonic antigen (CEA) levels for the tumor response to preoperative CRT in rectal cancer patients.

METHODS

The study comprised 141 rectal adenocarcinoma patients who underwent preoperative radiotherapy with 5-fluorouracil (FU) based chemotherapy, followed by radical surgery. The staging workup was consisted of endorectal ultrasound, abdominopelvic computed tomography scan, or magnetic resonance imaging. The outcome parameters were cancer-specific survival and disease-free survival. Pre-CRT clinicopathologic features, including age, gender, location of the tumor, clinical tumor (cT) classification, clinical nodal (cN) classification, and serum CEA levels were investigated as possible predictors for the response to preoperative CRT.

RESULTS

Pathologic complete or near complete responses (good responders, GR) occurred in 26 (19%) patients, while partial or no response (poor responders, PR) occurred in the remaining 115 (81%) patients. GR showed better cancer-specific survival (P = 0.028) and disease-free survival rates (P = 0.011) than PR. Univariate analysis revealed that positive cN and elevated (>5 ng/ml) pre-CRT serum CEA levels are associated with poor tumor response to preoperative CRT. Using logistic regression analysis, elevated pre-CRT serum CEA levels were the only significant predictor for the poor response to CRT (Odd ratio = 2.876, 95% confidence interval = 1.04-7.46, P = 0.041).

CONCLUSIONS

Our data suggest that elevated pre-CRT serum CEA levels are associated with poor tumor response to CRT. Therefore, pre-CRT serum CEA levels provide useful information about tumor response to preoperative CRT in rectal cancer patients.

Pathological complete response following pre-operative chemoradiotherapy in rectal cancer: analysis of phase II/III trials

Pathological complete response (pCR) has been used as a marker for the efficacy of pre-operative chemoradiotherapy (CRT) schedules in rectal cancer. To date there have been no randomized trials comparing CRT regimens in rectal cancer. Prospective phase II and CRT arms of randomized trials reported up to January 2004 were included, providing they defined the following minimum variables: drugs employed during CRT, radiotherapy dose and pCR rate. Multivariate analysis was used to examine the relationship of these variables on the pCR rate. In addition, the use of neoadjuvant chemotherapy, the type of publication (peer reviewed vs meeting abstract) and whether the tumours were stated to be unresectable/clinically fixed or to have threatened circumferential margins were investigated. The method of analysis was weighted linear modelling of the pCR rate which was normalized by the arcsine transformation. Phase II and phase III trials were identified including a total of 3157 patients. On multivariate analysis only the use of continuous infusion 5FU (p = 0.01), the use of a second drug (p = 0.001) and radiation dose (p = 0.02) were associated with higher rates of pCR. The use of a two drug regimen, the mode of delivery of 5FU and the radiation dose appear to be related to the incidence of pCR following CRT for rectal cancer. These results may generate hypotheses for future randomized trials. Important factors not considered in this analysis include the variability in pathological examination and in the time interval between CRT and surgery. In addition, the toxicity of the CRT regimens requires further investigation.

Does rectal wall tumor eradication with preoperative chemoradiation permit a change in the operative strategy?

PURPOSE

Preoperative chemoradiation may downstage locally advanced rectal cancer and, in some cases, with no residual tumor. The management of complete response is controversial and recent data suggest that radical surgery may be avoided in selected cases. Transanal excision of the scar may determine the rectal wall response to chemoradiation. This study was designed to assess whether the absence of tumor in the bowel wall corresponds to the absence of tumor in the mesorectum, known as true complete response.

METHODS

A retrospective review of the medical records of patients who underwent preoperative chemoradiation for advanced mid (6-11 cm from the anal verge) and low (from the dentate line to 5 cm from the anal verge) rectal cancer (uT2-uT3) followed by radical surgery with total mesorectal excision was undertaken. Patients in whom the pathology specimen showed no residual tumor in the rectal wall (yT0, "y" signifies pathologic staging in postradiation patients) were assessed for tumoral involvement of the mesorectum.

RESULTS

A total of 109 patients underwent preoperative, high-dose radiation therapy (94 percent with 5-fluorouracil chemosensitization), followed by radical surgery for advanced rectal cancer. Preoperatively, 47 patients were clinically assessed to have potentially complete response. After radical rectal resection, pathology did not reveal any residual tumor within the rectal wall (yT0) in 17 patients. In two (12 percent) of these patients, the mesorectum was found to be positive for malignancy: one had positive lymph nodes that harbored cancer; one had tumor deposits in the mesorectal tissue.

CONCLUSIONS

Compete rectal wall tumor eradication does not necessarily imply complete response, because the mesorectum may harbor tumor cells. Thus, caution should be exercised when considering the avoidance of radical surgery. Reliable imaging methods and clinical predictors for favorable outcome are important to allow less radical approaches in the future.

Oral chemotherapy in colorectal cancer treatment: review of the literature

Recent advances in anticancer treatment have focused on the development of oral anticancer agents with the intention of improving the patients' quality of life as well as providing therapeutic alternatives to intravenous chemotherapy. Until agents such as oxaliplatin and irinotecan became available, the treatment of colorectal cancer, one the most common cancers diagnosed in industralized countries, was mainly based on 5-fluorouracil modulation. The overwhelming majority of these new drugs are pyrimidine analogues intended to replace intravenous treatment or to make the therapy more acceptable to the patients. In this article, the use of oral chemotherapy, alone or in combination with radiotherapy, in colorectal cancer is reviewed and updated. The rationale for using oral compounds is discussed and newer agents, such as oral camptothecin analogues and antiangiogenic agents, are presented with the results of their clinical and preclinical developments.

Adjuvant radiation therapy of patients with rectal cancer

The standard in rectal cancer has been to add adjuvant radiation therapy to surgery in patients with stage II and III disease. Total mesorectal excision has led to lower local recurrence rates, and, if properly performed, may make adjuvant radiation unnecessary for certain stage II and III patients, such as T3 N0 patients with proximal lesions. There is also debate about the best method of delivering adjuvant radiotherapy. Preoperative radiotherapy at low dose per fraction with concurrent chemotherapy offers the advantages of maximizing sphincter preservation and greater tolerability. However, this will occasionally result in treating patients who are overstaged by ultrasound and may lead to greater postoperative morbidity and mortality than postoperative radiation. Preoperative radiotherapy has stronger data to support a survival advantage when added to surgery than postoperative radiation. Two randomized, phase III European studies may answer the question of which radiation technique is best for the near future. Protracted venous infusion of 5-fluorouracil (5-FU) is the standard method of radiosensitization. However, studies are ongoing using concurrent oxaliplatin, irinotecan, and oral 5-FU prodrugs. For now, we recommend that stage II and III rectal cancer patients receive protracted venous infusion 5-FU concurrent with preoperative radiation.

Preoperative chemoradiation using oral capecitabine in locally advanced rectal cancer

PURPOSE

Capecitabine (Xeloda) is a new orally administered fluoropyrimidine carbamate that was rationally designed to exert its effect by tumor-selective activation. We attempted to evaluate the efficacy and toxicity of preoperative chemoradiation using capecitabine in locally advanced rectal cancer.

METHODS AND MATERIALS

Between July 1999 and March 2001, 45 patients with locally advanced rectal cancer (cT3/T4 or N+) were treated with preoperative chemoradiation. Radiation of 45 Gy/25 fractions was delivered to the pelvis, followed by a 5.4 Gy/3 fractions boost to the primary tumor. Chemotherapy was administered concurrent with radiotherapy and consisted of 2 cycles of 14-day oral capecitabine (1650 mg/m(2)/day) and leucovorin (20 mg/m(2)/day), each of which was followed by a 7-day rest period. Surgery was performed 6 weeks after the completion of chemoradiation.

RESULTS

Thirty-eight patients received definitive surgery. Primary tumor and node downstaging occurred in 63% and 90% of patients, respectively. The overall downstaging rate, including both primary tumor and nodes, was 84%. A pathologic complete response was achieved in 31% of patients. Twenty-one patients had tumors located initially 5 cm or less from the anal verge; among the 18 treated with surgery, 72% received sphincter-preserving surgery. No Grade 3 or 4 hematologic toxicities developed. Other Grade 3 toxicities were as follows: hand-foot syndrome (7%), fatigue (4%), diarrhea (4%), and radiation dermatitis (2%).

CONCLUSION

These preliminary results suggest that preoperative chemoradiation with capecitabine is a safe, well-tolerated, and effective neoadjuvant treatment modality for locally advanced rectal cancer. In addition, this preoperative treatment has a considerable downstaging effect on the tumor and can increase the possibility of sphincter preservation in distal rectal cancer.