Peri-operative modulation of cellular immunity in patients with colorectal cancer

Nutritional, immunological and antioxidant defense status of outpatients diagnosed with colorectal cancer - a case-control study of the little-studied population

This cross-sectional study was conducted to investigate nutritional and immunological status of colorectal cancer (CRC) patients in a little-studied population from developing country, Pakistan. Data on 81 CRC patients and 37 healthy controls (HCs) were collected on nutritional status, nutrient intake, percent body fat (%BF), selected immunological parameters, phytochemical index (PI), healthy eating index (HEI), and prognostic nutrition index (PNI). Blood samples were used for immunological and antiradical defense potential (expressed as 50% hemolysis time; HT₅₀). Results show 40/81 (49.4%) patients reported weight loss in past 3-6 mo, Significant differences were found in HEI values between patients vs. HCs, and between patients in low vs. high PNI groups (P, for all trends <0.05). Patients in the higher PNI group were heavier, had higher % BF, higher energy intake, and higher PI score as compared to patients in the low PNI group (P < 0.05). Low PNI was positively associated with non-significantly lower CD4:CD8 ratios, higher B-cells and NK cells (P, for all trends >0.05), but with significantly higher hs-CRP levels, and lower HT₅₀ values (P, for all trends <0.001). In conclusion, CRC patients in a little-studied population have compromised nutritional and immunological health with lower HEI and PNI scores.

Safety of low-dose subcutaneous recombinant interleukin-2: systematic review and meta-analysis of randomized controlled trials

Standard-dose intravenous recombinant interleukin-2 (rIL-2) is indicated for the treatment of some subtypes of cancer; however, severe adverse events, including venous thromboembolism (VTE), may complicate its administration. Low-dose subcutaneous rIL-2 is being studied for the management of immune-mediated diseases, since it can modulate the immunological response by specifically targeting T regulatory (T_reg) cells; importantly, it is supposed to cause fewer or no complications. In this systematic review and meta-analysis of phase II-III randomized controlled trials (RCTs), we investigated the safety of low-dose (<6 Million International Unit [MIU]/day) and ultra-low-dose (≤1 MIU/day) rIL-2 for severe adverse events (grade III-V) with a focus on VTE. Data of 1,321 patients from 24 RCTs were analysed: 661 patients were randomized to the rIL-2 arm (on top of standard of care) and 660 patients to standard of care alone or placebo. Two studies reported higher rates of thrombocytopenia in the low-dose rIL-2 arm. Ultra-low-dose rIL-2 was reported to be well tolerated in 6 studies with a negligible rate of severe adverse events. Symptomatic VTE events were not reported in any of the study arms (absolute risk difference 0% [95%CI −0.1%; +0.1%]). Our results may facilitate the study and introduction in clinical practice of low-dose rIL-2 for potentially new indications.

The Potential for Cancer Immunotherapy in Targeting Surgery-Induced Natural Killer Cell Dysfunction

Natural Killer (NK) cells are granular lymphocytes of the innate immune system that are able to recognize and kill tumor cells without undergoing clonal selection. Discovered over 40 years ago, they have since been recognized to possess both cytotoxic and cytokine-producing effector functions. Following trauma, NK cells are suppressed and their effector functions are impaired. This is especially important for cancer patients undergoing the removal of solid tumors, as surgery has shown to contribute to the development of metastasis and cancer recurrence postoperatively. We have recently shown that NK cells are critical mediators in the formation of metastasis after surgery. While research into the mechanism(s) responsible for NK cell dysfunction is ongoing, knowledge of these mechanisms will pave the way for perioperative therapeutics with the potential to improve cancer outcomes by reversing NK cell dysfunction. This review will discuss mechanisms of suppression in the postoperative environment, including hypercoagulability, suppressive soluble factors, the expansion of suppressive cell populations, and how this affects NK cell biology, including modulation of cell surface receptors, the potential for anergy, and immunosuppressive NK cell functions. This review will also outline potential immunotherapies to reverse postoperative NK dysfunction, with the goal of preventing surgery-induced metastasis.

Phosphodiesterase-5 inhibition reduces postoperative metastatic disease by targeting surgery-induced myeloid derived suppressor cell-dependent inhibition of Natural Killer cell cytotoxicity

Cancer surgery while necessary for primary tumor removal, has been shown to induce immune suppression and promote metastases in preclinical models and human cancer surgery patients. Activating the immune system and reversing immunosuppression have emerged as promising ways to treat cancer and they can be safely employed in the perioperative period. In this study, we evaluated the immunotherapeutic potential of phosphodiesterase-5 (PDE-5) inhibitors to target surgery-induced myeloid-derived suppressor cells (MDSC) and restore natural killer (NK) cell function in the clinically relevant perioperative period. Immunocompetent murine tumor models of major surgery were used to characterize the functional suppression of surgery-induced MDSC and to assess the in vivo efficacy of perioperative PDE5 inhibition. In cancer surgery patients with abdominal malignancies, we assessed postoperative NK cell function following co-culture with MDSC and PDE5 inhibition. Perioperative PDE5 inhibition reverses surgery-induced immunosuppression. In particular, sildenafil reduces surgery-derived granulocytic-MDSC (gMDSC) function through downregulation of arginase 1 (ARG1), IL4Ra and reactive oxygen species (ROS) expression, enabling NK cell antitumor cytotoxicity and reducing postoperative disease recurrence. By removing surgery-derived immunosuppressive mechanisms of MDSCs, sildenafil can be combined with the administration of perioperative influenza vaccination which targets NK cells to reduce postoperative metastasis. Importantly, sildenafil reverses MDSC suppression in cancer surgery patients. These findings demonstrate that PDE5 inhibitors reduce postoperative metastasis by their ability to inhibit surgery-induced MDSC. Further clinical studies are warranted to investigate the immunotherapeutic role of PDE5 inhibitors in combination with cancer surgery.

Dysfunctional Natural Killer Cells in the Aftermath of Cancer Surgery

The physiological changes that occur immediately following cancer surgeries initiate a chain of events that ultimately result in a short pro-, followed by a prolonged anti-, inflammatory period. Natural Killer (NK) cells are severely affected during this period in the recovering cancer patient. NK cells play a crucial role in anti-tumour immunity because of their innate ability to differentiate between malignant versus normal cells. Therefore, an opportunity arises in the aftermath of cancer surgery for residual cancer cells, including distant metastases, to gain a foothold in the absence of NK cell surveillance. Here, we describe the post-operative environment and how the release of sympathetic stress-related factors (e.g., cortisol, prostaglandins, catecholamines), anti-inflammatory cytokines (e.g., IL-6, TGF-β), and myeloid derived suppressor cells, mediate NK cell dysfunction. A snapshot of current and recently completed clinical trials specifically addressing NK cell dysfunction post-surgery is also discussed. In collecting and summarizing results from these different aspects of the surgical stress response, a comprehensive view of the NK cell suppressive effects of surgery is presented. Peri-operative therapies to mitigate NK cell suppression in the post-operative period could improve curative outcomes following cancer surgery.

Attacking Postoperative Metastases using Perioperative Oncolytic Viruses and Viral Vaccines

Surgical resection of solid primary malignancies is a mainstay of therapy for cancer patients. Despite being the most effective treatment for these tumors, cancer surgery has been associated with impaired metastatic clearance due to immunosuppression. In preclinical surgery models and human cancer patients, we and others have demonstrated a profound suppression of both natural killer (NK) and T cell function in the postoperative period and this plays a major role in the enhanced development of metastases following surgery. Oncolytic viruses (OV) were originally designed to selectively infect and replicate in tumors, with the primary objective of directly lysing cancer cells. It is becoming increasingly clear, however, that OV infection results in a profound inflammatory reaction within the tumor, initiating innate and adaptive immune responses against it that is critical for its therapeutic benefit. This anti-tumor immunity appears to be mediated predominantly by NK and cytotoxic T cells. In preclinical models, we found that preoperative OV prevents postoperative NK cell dysfunction and attenuates tumor dissemination. Due to theoretical safety concerns of administering live virus prior to surgery in cancer patients, we characterized safe, attenuated versions of OV, and viral vaccines that could stimulate NK cells and reduce metastases when administered in the perioperative period. In cancer patients, we observed that in vivo infusion with oncolytic vaccinia virus and ex vivo stimulation with viral vaccines promote NK cell activation. These preclinical studies provide a novel and clinically relevant setting for OV therapy. Our challenge is to identify safe and promising OV therapies that will activate NK and T cells in the perioperative period preventing the establishment of micrometastatic disease in cancer patients.

Levels of lymphocyte subsets in peripheral blood prior treatment are associated with aggressive breast cancer phenotypes or subtypes

The aim of this study was to assess associations between ER, Ki67, Her-2 phenotypes, molecular subtypes of breast cancer and circulating levels of lymphocyte subsets (CD4+, CD8+, NK, CD19+, CD20+) and the ratio of CD4+ to CD8+ prior to treatment. Cells from peripheral blood were counted by flow cytometry, ER, Her-2, and Ki67 expressions were detected by pathological examination, and Her-2 was also detected by FISH. We conducted a case-case comparison of 494 women with newly diagnosed breast cancer to evaluate association between levels of lymphocyte subsets in peripheral blood and breast cancer phenotypes [ER- vs. ER+; Ki67 ≥ 14 % vs. Ki67 < 14 %; Her-2+ vs. Her-2-; triple-negative breast cancer (TNBC) vs. luminal A]. Women with the highest levels of CD3+ (OR 0.45, 95 % CI 0.22-0.94), CD4+ (OR 0.22, 95 % CI 0.08-0.59), and the ratio of CD4+/CD8+ (OR 0.17, 95 % CI 0.06-0.47) were least likely to have TNBCs compared with luminal A cancers. The highest tertile of CD8+ (OR 3.67, 95 % CI 1.06-12.72) and NK (OR 2.64, 95 % CI 1.12-6.24) was significantly associated with TNBC compared with luminal A cancer. ER-, Ki67 ≥ 14 %, Her-2+ were associated with low levels of CD4+ and CD4+/CD8+ compared with ER+, Ki67 < 14 %, Her-2-. Women in the highest level of CD8+ had more likelihood to have ER- and Her-2+ compared with ER+ and Her-2-. High levels of NK cells were associated with increased risk of ER- compared with ER+ cancers. Highest levels of CD19+ and CD20+ were associated with low risk of ER-, compared with ER+ cancers. These findings show that immune function differs among different breast cancer phenotypes or subtypes and is associated with ER-, Her-2+, Ki67 ≥ 14 %, and TNBC which are likely to be aggressive phenotypes.

Maraba MG1 virus enhances natural killer cell function via conventional dendritic cells to reduce postoperative metastatic disease

This study characterizes the ability of novel oncolytic rhabdoviruses (Maraba MG1) to boost natural killer (NK) cell activity. Our results demonstrate that MG1 activates NK cells via direct infection and maturation of conventional dendritic cells. Using NK depletion and conventional dendritic cells ablation studies in vivo, we established that both are required for MG1 efficacy. We further explored the efficacy of attenuated MG1 (nonreplicating MG1-UV(2min) and single-cycle replicating MG1-Gless) and demonstrated that these viruses activate conventional dendritic cells, although to a lesser extent than live MG1. This translates to equivalent abilities to remove tumor metastases only at the highest viral doses of attenuated MG1. In tandem, we characterized the antitumor ability of NK cells following preoperative administration of live and attenuated MG1. Our results demonstrates that a similar level of NK activation and reduction in postoperative tumor metastases was achieved with equivalent high viral doses concluding that viral replication is important, but not necessary for NK activation. Biochemical characterization of a panel of UV-inactivated MG1 (2-120 minutes) revealed that intact viral particle and target cell recognition are essential for NK cell-mediated antitumor responses. These findings provide mechanistic insight and preclinical rationale for safe perioperative virotherapy to effectively reduce metastatic disease following cancer surgery.

Perioperative influenza vaccination reduces postoperative metastatic disease by reversing surgery-induced dysfunction in natural killer cells

PURPOSE

Surgical removal of solid primary tumors is an essential component of cancer treatment. Surgery-induced dysfunction in natural killer (NK) cells has been linked to the development of metastases in animal models and patients with cancer. We investigated the activation of NK cells using influenza vaccine in the perioperative period to eradicate micrometastatic disease.

EXPERIMENTAL DESIGN

Both the B16lacZ and 4T1 tumor models in immunocompetent mice were used to assess the in vivo efficacy of perioperative influenza vaccine administration. In healthy human donors and cancer surgery patients, we assessed NK cell function pre- and post-influenza vaccination using both in vivo and ex vivo assays.

RESULTS

Using the TLR3 agonist poly(I:C), we showed as proof-of-principle that perioperative administration of a nonspecific innate immune stimulant can inhibit surgery-induced dysfunction in NK cells and attenuate metastases. Next, we assessed a panel of prophylactic vaccines for NK cell activation and determined that inactivated influenza vaccine was the best candidate for perioperative administration. Perioperative influenza vaccine significantly reduced tumor metastases and improved NK cytotoxicity in preclinical tumor models. Significantly, IFNα is the main cytokine mediator for the therapeutic effect of influenza vaccination. In human studies, influenza vaccine significantly enhanced NK cell activity in healthy human donors and cancer surgery patients.

CONCLUSION

These results provide the preclinical rationale to pursue future clinical trials of perioperative NK cell activation, using vaccination in cancer surgery patients. Research into perioperative immune therapy is warranted to prevent immune dysfunction following surgery and eradicate metastatic disease.

Preventing postoperative metastatic disease by inhibiting surgery-induced dysfunction in natural killer cells

Natural killer (NK) cell clearance of tumor cell emboli following surgery is thought to be vital in preventing postoperative metastases. Using a mouse model of surgical stress, we transferred surgically stressed NK cells into NK-deficient mice and observed enhanced lung metastases in tumor-bearing mice as compared with mice that received untreated NK cells. These results establish that NK cells play a crucial role in mediating tumor clearance following surgery. Surgery markedly reduced NK cell total numbers in the spleen and affected NK cell migration. Ex vivo and in vivo tumor cell killing by NK cells were significantly reduced in surgically stressed mice. Furthermore, secreted tissue signals and myeloid-derived suppressor cell populations were altered in surgically stressed mice. Significantly, perioperative administration of oncolytic parapoxvirus ovis (ORFV) and vaccinia virus can reverse NK cell suppression, which correlates with a reduction in the postoperative formation of metastases. In human studies, postoperative cancer surgery patients had reduced NK cell cytotoxicity, and we show for the first time that oncolytic vaccinia virus markedly increases NK cell activity in patients with cancer. These data provide direct in vivo evidence that surgical stress impairs global NK cell function. Perioperative therapies aimed at enhancing NK cell function will reduce metastatic recurrence and improve survival in surgical cancer patients.

Adjuvant therapy for completely resected stage II colon cancer

BACKGROUND

Colon cancer is potentially curable by surgery. Although adjuvant chemotherapy benefits patients with stage III disease, there is uncertainty of such benefit in stage II colon cancer. A systematic review of the literature was performed to better define the potential benefits of adjuvant therapy for patients with stage II colon cancer.

OBJECTIVES

To determine the effects of adjuvant therapy on overall survival and disease-free survival in patients with stage II colon cancer.

SEARCH STRATEGY

Ovid MEDLINE (1986-2007), EMBASE (1980-2007), and EBM Reviews - Cochrane Central Register of Controlled Trials ( to 2007) were searched using the medical headings "colonic neoplasms", "colorectal neoplasms", "adjuvant chemotherapy", "adjuvant radiotherapy" and "immunotherapy", and the text words "colon cancer" and "colonic neoplasms". In addition, proceedings from the annual meetings of the American Society of Clinical Oncology and the European Society of Medical Oncology (1996 to 2004) as well as personal files were searched for additional information.

SELECTION CRITERIA

Randomized trials or meta-analyses containing data on stage II colon cancer patients undergoing adjuvant therapy versus surgery alone.

DATA COLLECTION AND ANALYSIS

:Three reviewers summarized the results of selected studies. The main outcomes of interest were overall and disease-free survival, however, data on toxicity and treatment delivery were also recorded.

MAIN RESULTS

With regards to the effect of adjuvant therapy on stage II colon cancer, the pooled relative risk ratio for overall survival was 0.96 (95% confidence interval 0.88, 1.05). With regards to disease-free survival, the pooled relative risk ratio was 0.83 (95% confidence interval 0.75, 0.92).

AUTHORS' CONCLUSIONS

Although there was no improvement in overall survival in the pooled analysis, we did find that disease-free survival in patients with stage II colon cancer was significantly better with the use of adjuvant therapy. It seems reasonable to discuss the benefits of adjuvant systemic chemotherapy with those stage II patients who have high risk features, including obstruction, perforation, inadequate lymph node sampling or T4 disease. The co-morbidities and likelihood of tolerating adjuvant systemic chemotherapy should be considered as well. There exists a need to further define which high-risk features in stage II colon cancer patients should be used to select patients for adjuvant therapy. Also, researchers must continue to search for other therapies which might be more effective, shorter in duration and less toxic than those available today.

Immune function and adjustment style: do they predict survival in breast cancer?

The aim of this study was to investigate the role of immune status and psychosocial factors in survival from early breast cancer (N=61). Baseline assessments included lymphocyte number and function, natural killer cell activity (NKA), plasma cortisol and prolactin level. Psychosocial measures included anxiety, depression and mental adjustment to cancer and social support. Length of follow-up was 6.1-7.9 years with 14 (23%) breast cancer deaths. In Cox proportional hazards models adjusting for lymph node status two parameters predicted longer survival, low NKA (HR 29 per LLU, p=0.003) and minimizing the illness adjustment (HR 0.64 per scale point, p=0.012). These data provide little evidence for a psychoneuroimmunological mechanism in the survival from breast cancer. While this study is limited due to small sample size, and therefore the possibility of inflated estimates, longer survival in those minimizing the illness is a finding consistent with recent studies; however, the counter-intuitive finding that high NKA predicts shorter survival may be a marker for current disease or response to treatments.

Physical exercise and immune system function in cancer survivors: a comprehensive review and future directions

BACKGROUND

There are a limited number of interventions for cancer survivors following completion of primary therapy that might reduce the risk of cancer recurrence and/or secondary malignancies and increase survival times. It has been proposed that physical exercise may be beneficial by enhancing the anticancer immune system response. The purpose of the current article is to: 1) briefly describe the immune system response to tumors, 2) discuss the impact of anticancer therapy on immune system function in cancer survivors, 3) provide a systematic and comprehensive review of the extant literature examining physical exercise and immune system function in cancer survivors, and 4) offer a critical analysis of this literature and outline directions for future research.

METHODS

A comprehensive literature search up to March 2001 identified empirical articles that examined the effects of physical exercise training on immune system function in cancer survivors from CD-ROM database searches and manual searches.

RESULTS

To the authors' knowledge, six empirical studies published between 1994 and 2000 have examined physical exercise and immune system function in cancer survivors. Overall, four out of six studies reported statistically significant improvements in a number of cancer-related immune system components as a result of exercise. However, there are several limitations that must be considered when interpreting the findings of these studies. These limitations involve the samples, designs, physical exercise interventions, physical fitness assessments, and immunologic assessments.

CONCLUSIONS

Additional research is needed to determine if physical exercise in cancer survivors may reduce the risk of cancer recurrence and secondary malignancies and increase survival times.

Immune-stimulating effects of low-dose perioperative recombinant granulocyte-macrophage colony-stimulating factor in patients operated on for primary colorectal carcinoma

BACKGROUND

Surgery induces a postoperative immunosuppression, thereby possibly facilitating the outgrowth of pre-existing occult metastases or the seeding of disseminated tumour cells in patients with primary colorectal carcinoma operated on with curative intent. The hypothesis that adjuvant therapy with perioperative recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) would minimize postoperative immunosuppression was investigated in this pilot study.

METHODS

Patients were allocated randomly to receive daily subcutaneous injections with either saline (n = 8) or rhGM-CSF 2.8 microg per kg body-weight (n = 8) from 3 days before operation until 4 days afterwards. Phytohaemagglutinin (PHA) skin test reactivity, monocyte human leucocyte antigen (HLA) DR expression and the extent of the acute-phase response, by determination of white blood cell count and differentiation, plasma interleukin (IL) 6 levels and body temperature in the perioperative period, were examined.

RESULTS

rhGM-CSF treatment minimized postoperative suppression in PHA skin test reactivity and increased the numbers of neutrophils and monocytes while enhancing the expression of HLA-DR in the postoperative period. Additionally, both postoperative plasma IL-6 levels and the incidence of fever tended to be higher in the rhGM-CSF group.

CONCLUSION

In this pilot study, perioperative administration of low-dose rhGM-CSF stimulated certain immune functions that are normally depressed after operation. The implications for the antitumour responses directly after operation and the formation of liver metastases are currently under investigation.

Influence of peri-operative immunotherapy on serum cytokines and soluble cytokine receptors in patients undergoing surgery for colorectal cancer

OBJECTIVE

The cellular immune response is suppressed following surgery for colorectal cancer. As cytokines influence the patient's immunological responsiveness, we have measured serum cytokines and their soluble receptors in patients receiving peri-operative immunotherapy for colorectal cancer.

PATIENTS AND METHODS

Fifty-two patients were randomized to receive low dose recombinant IL-2 (rIL-2) alone; rIL-2 with interferon-alpha (IFN-α) or no immunotherapy. Serum cytokines and cytokine receptor levels were measured preoperatively and on post-operative days 1, 4, 7 and 10 using ELISA kits.

RESULTS

Circulating levels of IFN-γ were undetectable in the majority of patients, although IFN-γR levels were increased in all three groups on the first post-operative day (P < 0.05). Similarly, IL-2 was undetectable in most subjects and not enhanced by treatment. However, IL-2R was significantly induced in all patients (P < 0.001), and these levels were higher in both treatment groups when compared with control (P < 0.005). Tumour necrosis factor-alpha (TNF-α) was universally undetectable, but the TNF-R p55 and p75 subunits were induced in all patients (P < 0.005); and as with IL-2R, this was greater in the treatment groups (P < 0.01). Finally, IL-6 production was induced in all groups (P < 0.005), but this was only noted on day 1.

CONCLUSION

Soluble cytokine receptors are induced by surgery, and levels of IL-2R and TNF-R are enhanced by exogenous rIL-2 and rIL-2 with IFN-α. This augmentation suggests increased immunocompetence associated with low dose peri-operative immunotherapy.

Perioperative cimetidine application modulates natural killer cells in patients with colorectal cancer: a randomized clinical study

Thirty-eight colorectal cancer patients were randomly assigned to treatment group, which took cimetidine in the perioperative period, and control group to which no drug was given. Twenty healthy volunteers served as normal controls. NK cells were measured by immunocytochemical technique. The results showed that NK percentages before treatment in both groups of patients were significantly lower than those in normal controls (P < 0.05). NK cell percentages at admission, before operation, on the 2nd and the 10th postoperative days were 14.84 +/- 4.41, 15.74 +/- 3.75, 17.21 +/- 3.69, 21.05 +/- 4.54, respectively, for the treatment group, and 15.00 +/- 2.77, 13.05 +/- 2.46, 14.21 +/- 2.19, 15.58 +/- 1.68, respectively, for control group. The difference was statistically significant (P < 0.01), suggesting that the perioperative administration of cimetidine could help restore NK cells in colorectal cancer patients.

Relationship of curative surgery on natural killer cell activity in colorectal cancer

PURPOSE

Aim of this study has been to evaluate natural killer (NK) activity in patients with colorectal tumors before and after curative surgery.

METHODS

Forty colorectal cancer patients without distant metastases were stratified according to American Joint Committee on Cancer/International Union Against Cancer staging system into three categories: Stage I (n = 12), Stage II (n = 15), and Stage III (n = 13). All of them underwent curative resection, and there were no major postoperative complications. Venous blood samples were obtained preoperatively, at surgical wound closure, and on the 1st, 7th, and 21st postoperative days. Mononuclear cells were isolated over Ficoll-Hypaque (Lymphoprep, Nycomed Pharma AS, Oslo, Norway) gradients, and NK activity was assayed by evaluation of cytotoxic response against K562 cells. Normal NK activity was achieved from 15 healthy donors. Percentage relative increments in relation to preoperative levels were calculated for every postoperative sample, and t-test was used for statistical evaluation.

RESULTS

Before surgery, Stages II and III patients had lower levels of NK activity than healthy people (P < 0.05 and P < 0.001, respectively). NK activity always fell after surgery (Stage I: -18.48 +/- 11.42; Stage II: -16.93 +/- 13.57; Stage III: -35.29 +/- 12.03, at day 1 postsurgery) and appeared to rise slightly by the 21st postoperative day in Stage I patients (+4.87 +/- 12.41). Stage II, and especially Stage III, patients did show a significant recovery by the 21st postoperative day (+23.63 +/- 9.36 and +43.19 +/- 13.34, respectively). At this time, NK activity in these two groups was not significantly lower than in normal subjects (P > 0.05).

CONCLUSION

NK activity is depressed in colorectal cancer patients in relation to progression of illness, even at locoregional stages. Curative resection of tumors at Stages II and III has promoted a recovery of NK activity in patients with uneventful postoperative courses.

Natural killer cells and cancer

BACKGROUND

Natural cytotoxicity, mediated by natural killer (NK) cells and cell with lymphokine-activated killer (LAK) activity, is believed to play an important role in host anti-cancer mechanisms.

METHODS

The authors critically review recent publications on the role of natural cytotoxicity in patients with cancer.

RESULTS

In patients with cancer, several studies have noted variations in the numbers and activity of NK and cells with LAK activity in different body compartments. NK cell activity in the peripheral blood lymphocytes (PBLs) is higher than that found in lymph nodes and within tumors, and this appears to be due to the presence of suppressor factors. The natural cytotoxicity of PBLs in patients with different types of cancers varies. However, there appears to be a trend for natural cytotoxicity to be reduced in certain cancer patients, possibly related to tumor volume or dissemination. Anti-cancer treatments (e.g., surgery, hormonal modulation, radiotherapy and chemotherapy) can also result in suppression of natural cytotoxicity, although the long-term effect on response to treatment and development of metastases is at present unknown.

CONCLUSIONS

NK and LAK cells, through the use of immune biologic modifiers, have been demonstrated to have a therapeutic role in the treatment of human cancers. Further studies are required to determine the optimal dosages and combinations of chemotherapeutic agents, the timing of surgery, and the adjuvant use of immune biologic response modifiers. An increasing awareness and understanding of this field, may allow for the future development of anti-cancer therapies.

Adjuvant treatment of colon and rectal cancer: impact of chemotherapy, radiotherapy, and immunotherapy on routine postsurgical patient management. Forschungsgruppe Onkologie Gastrointestinaler Tumoren (FOGT)

Colon cancer patients with UICC stage III or T4 N0 M0 stage II should receive postoperative adjuvant therapy, since relapse rates are high and surgical outcome has been improved by adjuvant treatment. The standard treatment is 5-fluourouracil plus levamisole; an alternative option is the combination of 5-fluourouracil and folinic acid. Stage II (T3 N0 M0) colon cancer patients should not receive adjuvant treatment outside of studies. Rectal cancer patients of stage II or III should receive postoperative radiochemotherapy with 45-54.4 Gy and 5-fluourouracil as standard treatment. Patients not eligible for radiotherapy may receive adjuvant chemotherapy only. Studies need to be conducted to improve adjuvant therapy in colorectal cancer. All qualified patients should be treated within these studies requiring sufficient patient numbers, as well as comparable surgical procedures, proper patient selection and stratification criteria, drug and dose intensities. Intraportal infusion may be as effective as systemic adjuvant treatment; the tumor type and stage for which benefit from this kind of treatment is consistently significant needs to be defined, since intraportal infusion of all resectable colorectal cancers is overtreatment. Both surgery and histopathological staging may be improved in some centers, and these require standardization and quality control.